Unit 17 · The Twentieth-Century World

On June 28, 1914, a nineteen-year-old Bosnian Serb named Gavrilo Princip stepped up to an open car in Sarajevo and shot Archduke Franz Ferdinand, the heir to the throne of Austria-Hungary. The Archduke and his wife died within minutes. Princip belonged to a group that wanted Bosnia freed from Austrian rule and joined to Serbia. Austria-Hungary blamed the Serbian government and, a month later, declared war on Serbia. Five weeks after a killing in a Balkan town, most of Europe was at war.

How did one murder do that? The answer is the alliance system. Over the previous forty years the great powers had signed promises to defend one another. Germany backed Austria-Hungary. Russia backed Serbia and was tied to France. France was tied to Britain. When Austria moved against Serbia, Russia began to gather its army. Germany, fearing a war on two fronts, declared war on Russia and then on France. Its war plan called for knocking out France fast by marching through neutral Belgium. When German troops crossed the Belgian border, Britain declared war on Germany. That was August 4, 1914.

Alliances explain the speed, but not the willingness. For decades the powers had been competing. Germany and Britain raced to build bigger battleships. France wanted back the provinces it had lost to Germany in 1871. Russia and Austria-Hungary both wanted influence in the Balkans as the Ottoman Empire weakened. Each country had taken colonies in Africa and Asia and feared the others would take more. This mix of militarism, which means treating military strength as the highest goal, and nationalism, an intense loyalty to one’s own nation, made leaders confident that a short war would settle things in their favor.

Historians still argue over who was most to blame. Some point to Germany’s decision to back Austria without limit. Some point to Russia’s early mobilization, or to Austria’s harsh demands on Serbia, or to the generals in every capital whose plans left no time for talking. What the evidence shows clearly is that nobody in July 1914 was planning a four-year war that would kill about nine million soldiers. They expected the war they remembered, quick and decisive. They got something no one had seen before.

The machine gun changed everything. A single gun crew could fire hundreds of bullets a minute, and a line of them could stop a charging regiment in its tracks. Artillery, the big guns, could now hit targets miles away. Barbed wire slowed attackers while the guns found them. Against all this, the soldier of 1914 still had a rifle, a bayonet and his legs. Both sides quickly learned that the only way to survive was to dig. By the end of 1914 the Western Front was a double line of trenches, deep ditches roofed with sandbags and timber, stretching more than four hundred miles across France and Belgium.

Life in the trenches was misery even when no one was attacking. Water pooled at the bottom, and men who stood in it for days got trench foot, a rotting of the skin that could cost a man his toes. Lice lived in every seam of every uniform. Rats grew fat on the dead. Shells could fall at any moment, and a hit could bury a whole dugout. Soldiers spent days in the front line, then rotated back to rest, then returned. Many wrote that the waiting was worse than the fighting.

When generals did order an attack, the results were terrible. The usual plan was to pound the enemy trench with artillery for days, then send infantry walking across no man's land, the strip of ground between the lines. The shelling rarely cut all the wire or killed all the machine gunners. On July 1, 1916, the first day of the Battle of the Somme, the British army suffered about fifty-seven thousand casualties, nearly twenty thousand of them dead, and gained almost nothing. The battle continued until November. At Verdun that same year, French and German armies fought for ten months over a few square miles and lost hundreds of thousands of men between them.

New weapons kept arriving: poison gas in 1915, tanks in 1916, aircraft that grew from scouts into bombers. None broke the deadlock for long. What finally moved the front in 1918 was exhaustion on one side. Germany launched huge spring attacks, gained ground, and then ran out of men and food. Fresh American troops, more than a million of them by the summer, tipped the balance. On November 11, 1918, at eleven in the morning, the guns stopped. Soldiers on both sides could hardly believe the silence.

World War I was the first total war, a war in which a country’s entire economy and population are organized for fighting. Armies needed millions of shells a month, and only whole nations working together could make them. Governments took control of railroads, mines and factories. They told farmers what to grow and fixed the prices of bread and coal. In Germany, where a British naval blockade cut off imported food, the winter of 1916 to 1917 became known as the turnip winter because turnips were about all there was to eat. Hundreds of thousands of German civilians died of hunger and related disease during the war.

With so many men at the front, women filled the jobs they left. In Britain, France, Germany and later the United States, women made shells in munitions factories, drove streetcars, ran farms and worked as nurses close to the fighting. Munitions work was dangerous: the chemicals turned skin yellow, and explosions killed workers. Governments that had refused to let women vote now depended on their labor. In Britain, women over thirty won the vote in 1918. The United States passed the Nineteenth Amendment in 1920. The war did not cause these changes alone, but it made the old arguments against them hard to sustain.

Governments also went to war for people’s minds. Every side produced propaganda, posters and films and news stories designed to make people hate the enemy and support the war. Britain and France spread stories of German atrocities in Belgium, some true and some invented. Germany did the same in reverse. Governments censored letters from the front so families would not learn how bad things were. In the United States, which entered the war in April 1917, a new law made it a crime to speak against the draft, and about two thousand people were prosecuted for what they said or wrote.

Total war reached across oceans. Britain and France brought hundreds of thousands of soldiers and laborers from India, Africa, Vietnam and the Caribbean. The United States sent more than two million men to France, and about three hundred and seventy thousand Black Americans served, mostly in labor units, though some fought with distinction beside French troops. In Illinois, factories in Chicago, Rockford and East St. Louis ran around the clock. The war set patterns that would return, larger, in the next one.

By early 1917 Russia was breaking under the war. Its army had lost millions of men. Its railroads could not carry both soldiers and food. In Petrograd, the capital, women stood in line for bread in the freezing cold and found the shelves empty. On March 8, 1917, thousands of women marched to demand bread. Workers joined them. The tsar, Nicholas II, ordered soldiers to fire on the crowds, but the soldiers refused and joined the marchers instead. Within a week Nicholas gave up his throne. Three centuries of rule by his family were over.

A temporary government of moderate politicians took over and promised elections. It made one fatal choice: it kept Russia in the war. Soldiers kept dying and deserting. Peasants seized land from nobles without waiting for permission. In cities, councils of workers and soldiers called soviets began acting like governments of their own. Into this chaos came Vladimir Lenin, a revolutionary who had spent years in exile. Germany, hoping he would take Russia out of the war, sent him home by train in April. His slogan was simple: peace, land and bread.

Lenin led the Bolsheviks, a disciplined party that believed in communism: the idea that workers should own the factories and land together, with no private owners and, eventually, no classes at all. On the night of November 6 to 7, 1917, armed Bolshevik supporters seized the bridges, telegraph offices and the Winter Palace in Petrograd. There was little fighting. The temporary government simply collapsed. Lenin announced a new government, took Russia out of the war in March 1918 by giving Germany huge stretches of territory, and moved the capital to Moscow.

Then came a civil war, from 1918 to 1921, between the Bolshevik Reds and a loose alliance of Whites who ranged from monarchists to democrats. The Reds won, partly because the Whites could not agree on what they wanted. Millions died in the fighting and in the famine that followed. The Bolsheviks shut down other parties, created a secret police and shot the tsar and his family. In 1922 they named the country the Union of Soviet Socialist Republics. For the next seventy years, the existence of a communist great power would shape politics on every continent.

In January 1919 the victors met at Paris to write the peace. President Woodrow Wilson of the United States arrived as a hero. A year earlier he had laid out Fourteen Points for a fair peace: open diplomacy, freedom of the seas, the right of peoples to choose their own governments, and a League of Nations where countries would settle disputes by talking. The French leader, Georges Clemenceau, had other ideas. Germany had invaded France twice in fifty years. He wanted Germany weakened so it could never do so again. Britain’s David Lloyd George stood between them.

The treaty signed at Versailles on June 28, 1919, five years to the day after Sarajevo, was mostly Clemenceau’s. Germany lost about a tenth of its land and all its overseas colonies. Its army was limited to one hundred thousand men, with no air force, no submarines and no troops in the Rhineland along the French border. Article 231 made Germany accept responsibility for the war. On that basis Germany had to pay reparations, payments for the damage, set in 1921 at a sum so large that economists argued it could never be paid. Germans of every political view called it a dictated peace.

Other treaties broke up the losing empires. Austria-Hungary vanished, replaced by Austria, Hungary, Czechoslovakia and parts of Poland and Yugoslavia. The Ottoman Empire lost its Arab lands, which Britain and France took under a system called mandates. Wilson’s idea of self-determination, that each people should rule itself, guided some of the new borders. But every new country contained minorities who had wanted to be somewhere else, and the principle was not applied to Asians or Africans at all. Delegates from Vietnam, Egypt and India who came to Paris asking for it were turned away.

The League of Nations was created, but without the country whose president had invented it. The United States Senate refused to approve the treaty, mainly over fears that the League could drag America into future wars. Germany and Russia were kept out at first. The League had no army. When strong countries broke the rules in the 1930s, it could only protest. The peace of 1919 has been blamed for too much and too little. It was harsh enough to enrage Germany and too weak to hold Germany down. That combination proved dangerous.

In October 1929 prices on the New York stock market collapsed. People who had borrowed money to buy shares could not pay it back. Banks that had lent to them failed, taking savings with them. Businesses that could not borrow cut production and fired workers. Workers with no wages stopped buying. By 1933 about one in four American workers had no job. In Chicago, families camped in shacks along the river, and the city could not pay its teachers for months. The Great Depression was the worst economic collapse the industrial world had seen.

It did not stay in America. During the 1920s American banks had lent heavily to Germany, and Germany had used the money to pay reparations to Britain and France, who used it to pay war debts to the United States. When American lending stopped, the whole circle broke. German banks failed in 1931. By 1932 about six million Germans, roughly a third of the workforce, were unemployed. Countries tried to protect their own workers by raising tariffs, taxes on imported goods. The United States raised them sharply in 1930. Other countries answered in kind, and world trade fell by more than half between 1929 and 1933.

The suffering was everywhere but unequal. In Britain the old coal and shipbuilding towns emptied out. In Japan, farmers who depended on selling silk to America watched the price collapse. In Latin America, countries that sold coffee, copper or beef to the world lost their buyers overnight. Peasants in colonies from India to Indonesia saw the prices of their crops fall while their taxes did not. Governments that had promised prosperity now seemed helpless. People asked whether capitalism, an economy run by private owners and free markets, could work at all.

Different countries gave different answers. In the United States, Franklin Roosevelt’s New Deal put the government to work hiring the jobless, insuring bank deposits and paying pensions, all within a democracy. Sweden built a similar welfare system. The Soviet Union, cut off from world markets, reported no unemployment at all and drew admirers who did not see the costs. In Germany, Italy and Japan, the Depression helped bring to power men who promised order, jobs and greatness through force. The next lesson looks at them.

The first of the new dictators was Benito Mussolini in Italy. Italy had been on the winning side in 1918 but felt cheated by the peace, and strikes and street fighting shook the country. Mussolini, a former socialist turned nationalist, organized squads of black-shirted veterans who beat up his opponents. In 1922 he marched on Rome, and the king made him prime minister. Within a few years he had banned other parties and jailed critics. He called his movement fascism: the nation and its leader above everything, violence as a virtue, democracy as weakness. The word comes from the fasces, a bundle of rods that symbolized authority in ancient Rome.

Adolf Hitler admired Mussolini and copied him. His Nazi party blamed Germany’s defeat and misery on Jews, communists and the politicians who had signed the Versailles treaty. Through the prosperous late 1920s the Nazis were a fringe party. The Depression changed that. In the election of 1932 they became the largest party. On January 30, 1933, President Hindenburg made Hitler chancellor, believing he could be controlled. Within months Hitler had used a fire at the parliament building as an excuse to suspend civil rights, passed a law letting him rule by decree, banned other parties and opened the first concentration camp at Dachau. By 1934 he was the Führer, the leader, with no limits on his power.

Nazism was fascism with race at its center. Hitler taught that Germans were a master race and that Jews were a poison to be removed. The Nuremberg Laws of 1935 stripped German Jews of citizenship and banned marriage between Jews and other Germans. Jewish doctors, lawyers and teachers lost their jobs. On the night of November 9, 1938, Nazi mobs burned synagogues, smashed Jewish shops and sent about thirty thousand Jewish men to camps. Newspapers, radio, schools and youth groups all taught the same message. A state that tries to control every part of life this way is called totalitarian.

Joseph Stalin ruled the Soviet Union in the name of the opposite idea, communism, but his methods were much the same. From 1928 he forced peasants to give up their land to state-run collective farms. Those who resisted were shot or shipped to labor camps. The disruption caused a famine in 1932 and 1933, worst in Ukraine, that killed millions. Between 1936 and 1938 Stalin’s secret police arrested hundreds of thousands of party members, officers, and ordinary people on invented charges; many were shot after staged trials. Fascist and communist states hated each other, but each showed what a modern government could do to its own people when nothing was allowed to stand in its way.

The first move came in Asia. In 1931 Japan’s army seized Manchuria, a resource-rich region of northern China, and set up a puppet state. The League of Nations condemned the seizure. Japan simply walked out of the League. In 1937 Japan launched a full invasion of China. When its army took the capital, Nanjing, in December, soldiers murdered tens of thousands of prisoners and civilians and raped thousands of women over several weeks. Reports reached the outside world through diplomats, missionaries and journalists. The world protested and did nothing.

Mussolini watched and learned. In 1935 Italy invaded Ethiopia, one of only two independent countries left in Africa. Ethiopia’s emperor, Haile Selassie, went to the League in person to ask for help. The League voted for mild trade penalties that did not include oil, and Italy completed its conquest. Then Hitler began. In 1936 he marched troops into the Rhineland, which the Versailles treaty had forbidden. France and Britain protested and did nothing. In March 1938 he took over Austria. Crowds in Vienna cheered.

The crisis came over Czechoslovakia, where about three million Germans lived in a border region called the Sudetenland. Hitler demanded it. In September 1938, at Munich, the British prime minister Neville Chamberlain and the French premier agreed to give it to him in exchange for a promise that Germany wanted nothing more. Czechoslovakia was not invited. This policy of giving a hostile power what it demands to avoid war is called appeasement. Chamberlain came home saying he had secured peace. Six months later Hitler took the rest of Czechoslovakia.

Why did the democracies give way so long? The memory of 1914 to 1918 was the biggest reason: no one wanted another Somme. Many believed Versailles had been unfair and that Hitler only wanted to correct it. Britain and France were not ready to fight, and the United States had passed laws to keep out of any European war. The Soviet Union, distrusted by all, made its own deal. On August 23, 1939, Hitler and Stalin signed a pact promising not to attack each other and secretly agreed to divide Poland. On September 1, Germany invaded Poland. Two days later Britain and France declared war.

Germany’s new way of war was called blitzkrieg, lightning war: tanks, trucks and dive-bombers punching through a front and racing ahead before the enemy could react. Poland fell in five weeks. In the spring of 1940 the same method took Denmark, Norway, the Netherlands, Belgium and, in six weeks, France. Britain stood alone under a new prime minister, Winston Churchill. Through the summer and fall of 1940, German bombers tried to destroy the British air force and then British cities. They failed. Britain survived, and its survival kept a base from which the war could later be carried back to Europe.

In June 1941 Hitler broke his pact and invaded the Soviet Union with more than three million men, the largest invasion in history. German armies reached the edge of Moscow by December. Then winter and Soviet resistance stopped them. The decisive battle came at Stalingrad on the Volga River, where from the fall of 1942 into February 1943 the two armies fought street by street until the Germans were surrounded and about ninety thousand survivors surrendered. From then on the Red Army pushed west. The Soviet Union lost more people in the war than any other country, roughly twenty-seven million by the standard estimate, most of them civilians.

The Pacific war began on December 7, 1941, when Japanese planes struck the American fleet at Pearl Harbor, Hawaii, killing about twenty-four hundred Americans. The United States declared war on Japan the next day, and Germany declared war on the United States. Japan quickly took the Philippines, Malaya, Singapore, Burma and the Dutch East Indies. In June 1942, at the Battle of Midway, American carriers sank four Japanese carriers in a single day and the tide turned. American forces then fought island by island toward Japan, at Guadalcanal, Saipan, Iwo Jima and Okinawa, each bloodier than the last.

On June 6, 1944, D-Day, American, British and Canadian troops landed on the beaches of Normandy in France and opened a second front in the west. Germany was now squeezed between the Red Army and the Western Allies. Hitler killed himself in Berlin on April 30, 1945, and Germany surrendered on May 8. The war had involved more than fifty countries and killed somewhere between fifty and eighty million people, most of them civilians, through fighting, bombing, starvation and murder. Japan fought on through the summer of 1945. The last lessons of this chapter explain how its war ended.

The Nazis had persecuted Jews since 1933, but the war turned persecution into murder. When Germany conquered Poland in 1939, more than three million Polish Jews came under its control. They were forced into walled ghettos in cities like Warsaw, where hunger and disease killed thousands each month. When Germany invaded the Soviet Union in 1941, special killing squads followed the army, rounding up Jewish men, women and children, marching them to pits and shooting them. At Babi Yar, outside Kyiv, they killed more than thirty thousand people in two days in September 1941. By the end of the war these squads had shot well over a million people.

In January 1942 senior Nazi officials met at a villa in Wannsee, near Berlin, to organize what they called the final solution of the Jewish question: the murder of every Jew in Europe. The method was the death camp. At Auschwitz, Treblinka, Sobibor and other camps in occupied Poland, trains arrived from across Europe. Guards sorted the arrivals. Most were sent straight to gas chambers disguised as showers and killed with poison gas within hours. Their bodies were burned. A minority were worked to death. About one million Jews were killed at Auschwitz alone.

The Nazis also murdered Roma people, disabled people, Polish leaders, Soviet prisoners of war, gay men, political prisoners and Jehovah’s Witnesses. The total of Jews murdered in the Holocaust is about six million, roughly two out of every three Jews in Europe. The killing required thousands of ordinary participants: railway clerks, police, factory managers, neighbors who pointed out hiding places. It also had resisters. Jews rose in the Warsaw ghetto in 1943 and fought for nearly a month. Denmark’s people ferried almost all of the country’s Jews to safety in Sweden. Individuals across Europe hid families at the risk of their own lives.

How do we know? The Nazis kept records: train schedules, camp registers, reports from the killing squads listing the numbers shot. Allied armies photographed and filmed the camps they liberated in 1945. Survivors testified at the Nuremberg trials, where the top Nazi leaders were tried, and have kept testifying since. The word genocide, the deliberate destruction of a people, was coined in 1944 to name what had happened, and in 1948 the new United Nations made it a crime. The Illinois Holocaust Museum in Skokie, founded by survivors who settled near Chicago, is one of many places where that evidence is kept.

In 1939 physicists learned that splitting the nucleus of a uranium atom released enormous energy, and that a chain of such splits might make a bomb. Albert Einstein signed a letter warning President Roosevelt that Germany might build one first. The United States began a secret program, the Manhattan Project, that eventually employed more than a hundred thousand people. Its first great test happened in Illinois. On December 2, 1942, under the stands of an old football field at the University of Chicago, the physicist Enrico Fermi and his team started the world’s first controlled nuclear chain reaction. It lasted a few minutes. It proved the bomb was possible.

The first bomb was tested in the New Mexico desert on July 16, 1945. By then Germany had surrendered, and the question was Japan. Japan’s cities were already burning under American firebombing; one raid on Tokyo in March had killed around one hundred thousand people in a night. American planners expected an invasion of Japan to cost huge numbers of American and Japanese lives. President Harry Truman, who had taken office when Roosevelt died in April, decided to use the new weapon. On August 6 a single bomb destroyed the city of Hiroshima. On August 9 a second destroyed Nagasaki. Between them the bombs killed more than one hundred thousand people by the end of 1945, most of them civilians, and many more later from radiation.

On August 8 the Soviet Union declared war on Japan and poured into Manchuria. On August 15 Japan’s emperor announced surrender in a radio broadcast. Most Japanese had never heard his voice. The war was over. Historians still argue about the decision. Some hold that the bombs ended the war quickly and saved lives on both sides. Others argue that Japan was already close to surrender, that the Soviet entry mattered as much as the bombs, or that a demonstration should have been tried first. The evidence supports parts of several views, which is why the debate continues.

What no one disputes is what the bomb meant for the future. A single aircraft could now erase a city. The Soviet Union tested its own bomb in 1949, and within a decade both sides had weapons hundreds of times more powerful than the one dropped on Hiroshima. Scientists who had built the bomb became some of the loudest voices for controlling it. The Chicago team’s research grew into Argonne National Laboratory in the western suburbs, and the clock that Chicago scientists created to warn of nuclear danger, the Doomsday Clock, is still updated every year.

In the spring of 1945, while the fighting still raged, delegates from fifty countries met in San Francisco to write the charter of a new organization. The United Nations was meant to fix what the League of Nations had gotten wrong. Every member would sit in a General Assembly. But real power went to a Security Council whose five permanent members, the United States, the Soviet Union, Britain, France and China, could each block any action with a veto. The founders accepted this because the great powers would not join otherwise. The United States Senate approved the charter by a huge majority. This time America was in.

The United Nations did more than debate. It set up agencies to feed refugees, fight disease and help children, and in 1948 it adopted a Universal Declaration of Human Rights listing the rights every person should have. It also created a court to try disputes between nations. Yet the veto meant the Security Council could act only when the great powers agreed, and within two years they rarely did. The UN could not stop wars between superpowers. It could sometimes limit or end wars where the superpowers were willing to let it.

The war had also rearranged the world’s power. Britain and France were exhausted and deep in debt, and their empires in Asia and Africa would soon come apart. Germany and Japan lay in ruins under occupation. Two countries stood above the rest. The United States had lost about four hundred thousand soldiers but its cities were untouched, its factories were the world’s largest, and it alone held the atomic bomb. The Soviet Union had suffered terribly, but the Red Army now occupied every capital from Berlin to Sofia. These two superpowers had fought Hitler together. They agreed on little else.

By 1947 the alliance was over. Stalin installed obedient governments across Eastern Europe. The United States pledged to help any country resisting communist takeover. Germany, and Berlin inside it, was split into zones. The next chapter follows the long, strange conflict that resulted, called the Cold War because the two sides never fought each other directly. But it began here, in the ruins of a war that had killed tens of millions and ended with a weapon that could kill everyone. The question of the second half of the century was whether the world had learned enough to avoid a third.

In February 1945, with Germany nearly beaten, Roosevelt, Churchill and Stalin met at Yalta on the Black Sea. They agreed to divide Germany into occupation zones and promised free elections in the countries the Red Army had liberated. Stalin had a different idea of free. Within two years, communist parties backed by Soviet troops and secret police had taken over Poland, Hungary, Romania and Bulgaria. Opposition leaders were jailed or killed. In March 1946 Winston Churchill, speaking in Fulton, Missouri, said that an iron curtain had come down across Europe from the Baltic Sea to the Adriatic. The phrase stuck.

Each side saw the other as the aggressor. To Americans, Stalin was swallowing Eastern Europe and would take the rest if he could. To Stalin, whose country had been invaded from the west twice in thirty years and had lost twenty-seven million people, a ring of friendly governments was simple self-defense, and the American bomb was the real threat. In 1947, when Britain could no longer afford to support the Greek government against communist rebels, President Truman asked Congress for money and announced that the United States would help any free people resisting takeover. This containment policy, holding communism where it was, guided American action for forty years.

The first great test came in Berlin. The city lay deep inside the Soviet zone of Germany but was itself divided into four sectors. In June 1948, angry that the Western powers were creating a separate West German state, Stalin cut every road and rail line into West Berlin. Two million people faced starvation. Rather than fight through, the United States and Britain flew in food and coal, a plane landing every few minutes for nearly a year. In May 1949 Stalin gave up and reopened the roads. The airlift had shown that the West would hold its ground without firing a shot.

By 1949 the division was fixed. Germany became two countries. In August the Soviet Union tested its own atomic bomb, years earlier than American experts had expected. In October communists won the civil war in China, the world’s most populous country. Americans who had felt safe now felt surrounded. The Cold War was not a war in the old sense. The two sides never fought each other directly. It was a rivalry fought with money, spies, weapons, propaganda, and other people’s wars, and for four decades it shaped almost everything that happened on the planet.

Two years after the war, Western Europe was still broken. Cities lay in rubble, factories had no fuel, and the winter of 1947 was one of the coldest on record. Hungry, jobless people were voting for communist parties in France and Italy. In June 1947 the American Secretary of State, George Marshall, proposed that the United States pay to rebuild Europe. Over four years the Marshall Plan sent about thirteen billion dollars, a huge sum then, in food, machinery and raw materials to sixteen countries. The Soviet Union refused to take part and forbade its satellites to join. Western Europe’s economy recovered faster than anyone had predicted.

The plan was generous and it was also strategy. Americans reasoned that prosperous people would not vote for communism, and that a rebuilt Europe would buy American goods. Both things happened. Then the Berlin blockade convinced Western leaders that they needed more than money. In April 1949 the United States, Canada and ten Western European countries signed the North Atlantic Treaty. Its key clause said that an attack on any member would be treated as an attack on all. This alliance, NATO, was the first peacetime military alliance the United States had ever joined. It broke with a tradition of avoiding foreign entanglements that went back to George Washington.

The Soviet Union built a mirror image. Its economic answer to the Marshall Plan tied the economies of Eastern Europe to Moscow. When West Germany joined NATO in 1955, the Soviet Union and its seven satellites signed the Warsaw Pact, a military alliance under Soviet command. On paper it was an alliance of equals. In practice, Soviet troops stayed in each member country, and when Hungarians rose against their government in 1956 and Czechoslovaks tried to reform theirs in 1968, Warsaw Pact tanks crushed them. NATO protested and did nothing, because doing something risked nuclear war.

Europe thus settled into two armed camps that faced each other across a line running through the middle of Germany. Behind that line, the two blocs built two different ways of life. Western Europe combined capitalism with welfare states, elections and open borders among its members. Eastern Europe had state-owned economies, one-party rule, and borders that its own citizens could not cross. The gap in wealth between the two halves grew every year, and people on the eastern side could see it on Western television. That gap, more than any army, eventually decided the contest.

In 1952 the United States tested a hydrogen bomb hundreds of times more powerful than the one that destroyed Hiroshima. The Soviet Union tested its own the next year. In October 1957 the Soviets launched Sputnik, the first satellite, which meant a rocket could now carry a bomb across an ocean in half an hour. Americans were shaken. Both sides built missiles by the thousands, in underground silos, on bombers, and on submarines hidden under the sea. By the 1980s the two arsenals together held tens of thousands of warheads, enough to destroy every large city on Earth.

Strategists gave this situation a name that was also a description: mutual assured destruction, or MAD. If either side attacked, the other would still have enough weapons left to destroy the attacker. So neither side could win, and neither dared start. Some argued that the bomb had therefore prevented a third world war. Others pointed out that it had come frighteningly close to failing. Schoolchildren in Chicago and every other American city practiced hiding under their desks. Families built fallout shelters in their basements. The threat of the bomb was part of daily life.

The Cuban Missile Crisis of October 1962, covered in the next section, scared both sides enough to begin talking. A telephone hotline linked Washington and Moscow. In 1963 they agreed to stop testing bombs in the air. In the early 1970s President Richard Nixon and the Soviet leader Leonid Brezhnev signed the first treaty limiting missile numbers, and Nixon traveled to both Moscow and, in 1972, to communist China, which had split with the Soviet Union. This easing of tension was called détente, a French word for relaxing. It did not end the rivalry, but it made the rivalry more predictable.

Détente faded in the late 1970s and the arms race sped up again. Then in the mid-1980s a new Soviet leader, Mikhail Gorbachev, and President Ronald Reagan, who had called the Soviet Union an evil empire, surprised the world by becoming partners. In 1987 they signed a treaty that for the first time eliminated an entire class of nuclear missiles rather than just limiting them. Verification teams from each country inspected the other’s bases. The bomb had not gone away. But the two men who controlled most of them had decided that having fewer was safer than having more.

China had been at war with itself, on and off, since the 1920s. On one side stood the Nationalists under Chiang Kai-shek, backed by the United States. On the other stood the communists under Mao Zedong, who built their strength among peasants in the countryside. The Japanese invasion of 1937 nearly destroyed the Nationalist armies, while the communists grew by fighting behind Japanese lines. When the civil war resumed after 1945, Mao’s forces won. On October 1, 1949, he proclaimed the People’s Republic of China in Beijing. Chiang fled to the island of Taiwan, which the United States protected. Two Chinas claimed to be the real one.

Mao’s new state took land from landlords and gave it to peasants, then took it back into collective farms. In 1958 he launched the Great Leap Forward, ordering villages to make steel in backyard furnaces and report impossible harvests. The result was the deadliest famine of the century, with estimated deaths in the tens of millions between 1959 and 1961. In 1966 Mao unleashed the Cultural Revolution, sending bands of young Red Guards to attack teachers, officials and anyone accused of old thinking. Schools closed for years. Mao died in 1976, and his successors quietly began to undo much of what he had built.

Korea had been split at the end of World War II along the thirty-eighth parallel, Soviet troops in the north and American in the south. On June 25, 1950, North Korean forces crossed the line. Within weeks they held almost the whole peninsula. Because the Soviet delegate was boycotting the UN Security Council that month, the United States got the UN to authorize a force under General Douglas MacArthur. A daring landing at Inchon in September cut the North Korean army in half, and UN troops pushed north almost to the Chinese border. Then, in November, hundreds of thousands of Chinese soldiers poured across it.

The war seesawed back to the middle and then froze there. Fighting dragged on until an armistice, a stop to the fighting without a peace treaty, was signed in July 1953. The line ended up almost where it had begun. About thirty-six thousand Americans died, and Korean deaths, soldiers and civilians together, ran into the millions. Korea is still divided. The war showed the pattern of the whole Cold War: the superpowers never fought each other directly, but the countries in between paid the price. Korea also convinced Americans to keep a large army forever and to see every communist gain, anywhere, as a Soviet move.

Cuba lies about ninety miles from Florida. In 1959 a young lawyer named Fidel Castro led a rebel army that overthrew a corrupt dictator friendly to the United States. Castro took over American-owned sugar mills and oil refineries, and when Washington cut off trade, he turned to the Soviet Union. In April 1961 the United States armed and landed about fourteen hundred Cuban exiles at the Bay of Pigs to overthrow him. The invasion failed within three days. Castro declared himself a communist, and the Soviet leader Nikita Khrushchev saw a chance to plant weapons at America’s door.

In the summer of 1962 Soviet ships secretly carried nuclear missiles to Cuba. On October 14 an American spy plane photographed the launch sites under construction. President John F. Kennedy and his advisers debated for a week in secret. The generals urged air strikes and invasion. Kennedy feared that would kill Soviet troops and start a war in Europe. On October 22 he went on television, showed the world the photographs, and announced a naval quarantine: American warships would stop any vessel carrying weapons to Cuba. Soviet ships kept coming. The world waited to see whether they would stop.

For the next six days nothing was certain. Soviet ships turned back from the quarantine line. But work on the missile sites continued, an American spy plane was shot down over Cuba, and American forces went to their highest alert short of war. Khrushchev sent two letters, one emotional and offering to remove the missiles if the United States promised not to invade Cuba, and a second, harder, demanding that America also remove its missiles from Turkey. Kennedy answered the first letter publicly and, through his brother Robert, secretly promised to remove the Turkish missiles later. On October 28 Khrushchev announced the missiles would go.

Decades later, records showed how close it had been. Soviet commanders in Cuba had short-range nuclear weapons and might have used them against an invasion. A Soviet submarine officer, out of contact and believing war had begun, refused to agree to fire a nuclear torpedo. Both leaders had been pushed by their own advisers to be tougher, and both had chosen a way out that let the other save face. The crisis led directly to the hotline and the test ban treaty. It also taught both sides a lesson they never forgot: in a nuclear world, an enemy needs an exit.

Vietnam had been a French colony since the 1800s. On September 2, 1945, days after Japan’s surrender, a nationalist and communist named Ho Chi Minh declared Vietnam independent in Hanoi, opening his speech with words borrowed from the American Declaration of Independence. France refused to let go. After eight years of war, French forces were surrounded and defeated at Dien Bien Phu in 1954. A conference at Geneva split Vietnam temporarily at the seventeenth parallel, with Ho’s communists in the north and a government friendly to the West in the south, and promised elections to reunite it. The elections were never held. The United States feared Ho would win them.

American leaders believed in the domino theory: if Vietnam fell to communism, its neighbors would fall one after another. So they backed South Vietnam with money, advisers, and after 1965 with soldiers, more than half a million by 1969. The enemy was the North Vietnamese army and southern guerrillas called the Viet Cong, who fought from the villages and jungle, struck and vanished. American forces had the firepower to win any battle and no way to win the war. Bombing, chemical defoliants and the burning of villages turned many Vietnamese against the Americans and turned many Americans against the war. In January 1968 the communists launched the Tet Offensive, attacking cities across the south; they were beaten back, but television showed Americans a war their leaders had said was nearly won.

Protests grew, especially on college campuses. In 1968 Chicago’s Democratic convention was surrounded by demonstrators and police clashes filled the news. President Nixon slowly withdrew American troops while widening the bombing, and in January 1973 signed an agreement that got the last of them out. Two years later, in April 1975, North Vietnamese tanks rolled into Saigon and the war ended with a united communist Vietnam. About fifty-eight thousand Americans had died. Vietnamese deaths, north and south, soldiers and civilians, are estimated at well over a million. The dominoes did not fall beyond Vietnam’s immediate neighbors.

The Soviet Union then made a mirror-image mistake. In December 1979 it sent its army into Afghanistan to prop up a failing communist government. Afghan fighters called mujahideen, armed by the United States, Pakistan and Saudi Arabia, fought a guerrilla war from the mountains. Soviet firepower could take any valley and hold none. After nine years and about fifteen thousand Soviet dead, along with perhaps a million Afghans, Gorbachev withdrew the last troops in February 1989. The war drained Soviet money and morale at the moment its empire was cracking. Afghanistan itself fell into civil war, with consequences that reached the United States in 2001.

In 1930 a thin man of sixty in a homespun cloth walked from his home in western India toward the sea, about two hundred and forty miles, with a growing crowd behind him. When Mohandas Gandhi reached the beach at Dandi, he picked up a lump of salt. Under British law only the government could make salt, and every Indian paid a tax on it. Gandhi’s act was a crime, and he meant it to be. Across India tens of thousands followed his example, and the British jailed about sixty thousand people. The Salt March showed the world a new kind of weapon, and it showed Indians that the empire could be defied.

Gandhi called his method satyagraha, which he translated as truth force. It meant refusing to obey unjust laws, accepting arrest and beating without striking back, and treating even the oppressor as a person who could change. It required more discipline than fighting. Gandhi trained in South Africa, where he had spent twenty years defending Indian workers against discrimination. He also believed that India must be one nation of Hindus, Muslims, Sikhs and everyone else. Many Indians disagreed with his tactics, and the Muslim League, led by Muhammad Ali Jinnah, came to demand a separate Muslim state.

World War II broke Britain’s grip. Britain had used India’s soldiers and money without asking, and Indian leaders were jailed for demanding independence in return. After the war Britain was bankrupt, and a new government decided to leave. The question was whether to leave one country or two. As violence between Hindus and Muslims spread in 1946 and 1947, Britain agreed to partition: India for the Hindu majority, Pakistan, in two pieces a thousand miles apart, for Muslims. Independence came at midnight on August 14 to 15, 1947. Gandhi refused to celebrate. He spent the day fasting for peace.

Partition set off one of the largest migrations in history. Something like fifteen million people crossed the new borders in both directions, Muslims to Pakistan and Hindus and Sikhs to India. Trains arrived full of the dead. Estimates of the killed run from several hundred thousand to over a million. In January 1948 a Hindu extremist who thought Gandhi too generous to Muslims shot him dead in Delhi. India and Pakistan have fought several wars since. Yet India became, and has remained, the world’s largest democracy, and Gandhi’s method traveled: Martin Luther King Jr. studied it, and civil rights marchers in Chicago and Selma used it.

At midnight on March 6, 1957, a crowd gathered in the capital of the British colony of the Gold Coast. The British flag came down. The flag of a new nation, Ghana, went up. Its first leader, Kwame Nkrumah, had studied in the United States. He had organized strikes and boycotts. The British had jailed him, then released him to govern. Ghana was the first colony in sub-Saharan Africa to win independence. Nkrumah told the crowd that its freedom meant nothing unless it was linked to the freedom of the whole continent. Across Africa, people listened.

The colonial powers had been weakened by World War II, and African soldiers who had fought in it came home asking why they should be ruled by strangers. The Cold War also helped: both superpowers, for their own reasons, said they opposed old-style empires. In 1960 alone, seventeen African countries became independent, most of them former French colonies. Britain let its colonies go over the next decade, usually after negotiations. Belgium abandoned the huge Congo in 1960 with almost no preparation, having trained only a handful of Congolese as doctors, officers or administrators, and the country fell into chaos within days.

Where many European settlers lived, independence came through war. In Algeria, more than a million French settlers wanted to stay French. The war from 1954 to 1962 killed hundreds of thousands of Algerians and involved torture and terror on both sides before France finally withdrew. In Kenya, Britain fought a rebellion in the 1950s and held tens of thousands of Kikuyu people in camps. Portugal clung to Angola and Mozambique until 1975. In each case, independence came, but the memory of the fighting shaped the new states.

Independence did not undo the colonial past. The new borders had been drawn in Europe in the 1880s and cut across peoples and languages, leaving nearly every state with groups that distrusted one another. Colonial economies had been built to export one or two raw materials, cocoa or copper or oil, and the price of those was set abroad. Many new leaders, including Nkrumah, became dictators, and armies overthrew governments in country after country. The superpowers backed rival sides in civil wars in Angola, Ethiopia and elsewhere. Africans had won the right to govern themselves. Whether they could build the states they wanted was a struggle that continued.

After World War I Britain had governed Palestine under a League of Nations mandate, and had promised, in 1917, to support a national home there for Jewish people while protecting the rights of the Arabs who lived there. Jewish immigration grew, especially as Nazi persecution spread, and Arab and Jewish communities clashed. After the Holocaust, pressure for a Jewish state became overwhelming. In November 1947 the United Nations voted to divide Palestine into a Jewish state and an Arab state. Jewish leaders accepted the plan. Arab leaders rejected it, and fighting began at once.

On May 14, 1948, David Ben-Gurion proclaimed the State of Israel. The next day the armies of neighboring Arab countries attacked. Israel won, and by the armistice of 1949 it held more land than the UN plan had given it. During the war, roughly seven hundred thousand Palestinian Arabs fled or were driven from their homes and were not allowed to return. They and their descendants, now numbering in the millions, are the Palestinian refugees whose situation remains unresolved. Israelis call 1948 the War of Independence. Palestinians call it the Nakba, the catastrophe. Both names describe real events.

The conflict became part of the Cold War. The Soviet Union armed Egypt and Syria; the United States became Israel’s main supporter. In June 1967 Israel, striking first against Egyptian forces massing on its border, defeated Egypt, Syria and Jordan in six days and occupied the West Bank, Gaza, the Sinai and the Golan Heights, placing about a million more Palestinians under its rule. In October 1973 Egypt and Syria attacked on the Jewish holy day of Yom Kippur; Israel recovered, but only after heavy losses and an American airlift. Arab oil states then cut production and stopped shipments to the United States. Gasoline prices in Illinois and everywhere else jumped, and lines formed at the pumps.

The oil embargo taught the world that the region’s oil was a weapon, and it made the Persian Gulf a vital interest for both superpowers. In 1978 President Jimmy Carter brought the leaders of Egypt and Israel to Camp David, and Egypt became the first Arab state to make peace with Israel. Then in 1979 a revolution in Iran overthrew a pro-American king and created an Islamic republic hostile to both superpowers. Radicals held fifty-two Americans hostage for over a year. The Middle East would keep proving that the Cold War’s two-sided map could not explain everything.

In 1948 the National Party won an election in South Africa in which only white people could vote, and it made apartheid, an Afrikaans word for apartness, the law of the land. Every person was classified by race. Black South Africans, about three-quarters of the population, were assigned to scattered homelands that made up about thirteen percent of the country’s land. They needed passes to enter white cities, where they worked in mines and kitchens but could not live. Marriage across race lines was a crime. Beaches, buses, schools and hospitals were separate and grossly unequal. It was a system for keeping cheap labor and total power in white hands.

Resistance was led by the African National Congress, or ANC, which for years followed Gandhi’s methods of nonviolent protest. In March 1960 police at Sharpeville opened fire on a crowd protesting the pass laws and killed sixty-nine people, most shot in the back. The government banned the ANC. One of its young leaders, a lawyer named Nelson Mandela, concluded that nonviolence alone would not work and helped form an armed wing that sabotaged power lines and government buildings. He was captured, and in 1964 he was sentenced to life in prison. He spent twenty-seven years there, much of it breaking rocks on Robben Island.

Inside South Africa, protest never stopped. In 1976 schoolchildren in the township of Soweto marched against being taught in Afrikaans, and police killed hundreds in the months that followed. Outside, the world slowly turned against apartheid. Athletes were banned from international sports. Students in the United States, including at Illinois campuses, demanded that their universities sell shares in companies doing business in South Africa. In 1986 Congress passed economic sanctions over President Reagan’s veto. The Cold War had given South Africa’s government cover, since it called every opponent a communist. As the Cold War ended, the cover disappeared.

In February 1990 the new president, F. W. de Klerk, released Mandela and legalized the ANC. Four years of hard negotiation followed, while violence between rival groups killed thousands. Mandela insisted that the goal was not revenge but a country that belonged to everyone. In April 1994 South Africans of every race lined up, some for hours, in the first election in which all adults could vote. Mandela became president. A commission then heard testimony from victims and perpetrators of apartheid crimes, offering amnesty for full confession. Apartheid’s legal structure was gone. Its economic legacy, and the argument over how to repair it, remains.

Mikhail Gorbachev became leader of the Soviet Union in 1985 and found a country that was losing. Its factories made shoddy goods. Its farms could not feed the country without buying American grain. Its war in Afghanistan was a disaster. The arms race with a richer America was bankrupting it. Gorbachev announced two policies. Glasnost, meaning openness, let newspapers and citizens criticize the government for the first time in sixty years. Perestroika, meaning restructuring, loosened state control of the economy. He also told the leaders of Eastern Europe that the Soviet army would no longer save them from their own people.

Poland moved first. Its independent trade union, Solidarity, had been founded in the Gdansk shipyard in 1980 by an electrician named Lech Walesa and had survived years of being banned. In 1989 the government, unable to fix the economy, agreed to talks and then to partly free elections in June. Solidarity won almost every seat it was allowed to contest. By late summer Poland had a non-communist prime minister and no tanks had moved. Hungary, watching, dismantled the barbed wire on its border with Austria in May and opened it fully in September. The hole in the iron curtain let East Germans out, and that led to the events in Berlin described at the start of this chapter.

After the wall opened on November 9, the rest came in weeks. In Czechoslovakia, huge crowds in Prague filled the squares night after night, jingling their keys, and by the end of December the playwright Václav Havel, jailed by the communists months earlier, was president. Bulgaria’s leader was pushed out. Only in Romania was there blood: the dictator Nicolae Ceausescu ordered troops to fire on protesters, the army turned against him, and he was executed on Christmas Day. In one year, six governments that had seemed permanent were gone, almost all without a shot fired.

Not every communist government fell. In China, students had filled Beijing’s Tiananmen Square in the spring of 1989 demanding reform, and on the night of June 3 to 4 the army cleared the square with tanks and gunfire, killing hundreds or more. China’s rulers kept power by choosing force. Eastern Europe’s rulers, without Soviet backing and unwilling to order a massacre, did not. Historians point to many causes for 1989: economic failure, Gorbachev’s choices, Western pressure, the pope’s support for Poland, television. But the sequence of the year shows one thing clearly. Once people stopped being afraid, the system had nothing else to hold it up.

Gorbachev’s openness had a result he did not intend. The Soviet Union was made of fifteen republics, Russia by far the largest, and once people could speak freely, many said they wanted out. The three Baltic republics of Lithuania, Latvia and Estonia, seized by Stalin in 1940, formed a human chain of about two million people across all three countries in August 1989 to demand independence. Georgians, Armenians, Ukrainians and others followed. Meanwhile the half-reformed economy produced shortages worse than before. Shelves in Moscow stood empty. Gorbachev was praised abroad and increasingly hated at home.

In August 1991 a group of hard-line generals and party officials tried to stop the breakup. They placed Gorbachev under house arrest at his vacation home and sent tanks into Moscow. Boris Yeltsin, the elected president of the Russian republic, climbed onto one of those tanks outside the Russian parliament and called on the people to resist. Crowds surrounded the building. Soldiers refused to fire. Within three days the coup had collapsed. Gorbachev returned to Moscow, but power had passed to Yeltsin, who banned the Communist Party in Russia.

The republics now left one after another. Ukraine voted for independence in December by more than ninety percent. On December 8 the leaders of Russia, Ukraine and Belarus met and declared that the Soviet Union no longer existed. On December 25, 1991, Gorbachev resigned, and that evening the red flag over the Kremlin was lowered for the last time and the Russian flag raised. Seventy-four years after Lenin’s revolution, the state it had created was gone. The Cold War was over, and no shot had been fired between the superpowers.

The end raised questions the world is still answering. Fifteen new countries appeared, several with nuclear weapons on their soil, which were eventually moved to Russia. Russia’s economy collapsed in the 1990s and its people’s savings vanished, leaving bitterness that later leaders would use. Some Americans concluded that their side had won and that history had settled the question of how to govern. Others noted that the Soviet Union fell mainly from inside. The next chapter picks up in the world that this ending made: one superpower, dozens of new states, and an economy, and a set of problems, that no single country could contain.

In 1969 a computer at the University of California sent the first message over a network built for the American defense department. The message was supposed to be the word login. The system crashed after two letters. For twenty years the network, called ARPANET and then the Internet, connected mainly universities and research labs. Then in 1989 a British scientist named Tim Berners-Lee, working at a physics lab in Switzerland, proposed a way to link documents on any computer to documents on any other. He called it the World Wide Web and gave it away free. By 1995 about sixteen million people were online. By 2005 about a billion. Today it is more than five billion, most of them through a phone.

The change was not only in speed. The internet erased distance for information. A doctor in Chicago can read a study published in Tokyo an hour after it appears. A student in Kenya can take a free course from a university in Massachusetts. A factory in Vietnam receives its design files from Germany overnight. Companies could now split work across continents and coordinate it in real time, which made the global supply chains in this chapter’s opening story possible. Whole industries appeared, from search engines to ride-hailing, and others such as travel agencies and record stores nearly vanished.

The smartphone, introduced in its modern form in 2007, put all of this in a pocket. For billions of people in Africa and Asia, a phone was their first camera, bank account, newspaper and map. Farmers check crop prices before walking to market. Migrants send money home by text. Protesters in Tunisia and Egypt in 2011 organized on social media faster than governments could react. At the same time, governments learned to use the same tools. China built a system that blocks foreign websites and tracks its citizens online. Companies in the United States built businesses on collecting what users click, watch and buy.

The internet is a network, a web with no center, and that shape explains both its strength and its danger. No government owns it. Anyone can publish. That freed voices that had never been heard and also freed liars, scammers and mobs. The same tools that let a village clinic order medicine let a criminal in one country empty a bank account in another. The last section of this chapter returns to the question that the internet made urgent for every citizen: with everyone able to speak, how do you know whom to believe?

In 1994 the United States, Canada and Mexico joined in the North American Free Trade Agreement, removing most tariffs among them. In 1995 the World Trade Organization was founded to write and enforce trade rules for the whole world; it now has more than one hundred and sixty members. Together with the container ship and the internet, these rules made it cheap and safe to build a product across many countries. World trade grew far faster than the world economy. A company in Peoria could now sell tractors in Brazil and buy parts from Poland, and a shopper in Springfield could buy a television for a fraction of what it had cost her parents.

The gains were real and huge. Between 1990 and 2019 the share of the world’s people living in extreme poverty, on less than about two dollars a day, fell from roughly one in three to under one in ten. Most of that change came in Asia, where factories making goods for export pulled hundreds of millions off farms and into cities. Life expectancy rose, child deaths fell, and more girls went to school than at any time in history. Economists who disagree about almost everything mostly agree that open trade made the world as a whole richer.

But the world as a whole is not a person. The gains and losses landed on different people. In the American Midwest, factories that had paid good wages to workers without a college degree closed as production moved to Mexico or China. Towns like Galesburg, Illinois, where a large appliance plant shut in 2004 and moved to Mexico, lost their largest employer and never fully recovered. Economists found that regions hit by import competition saw lasting drops in jobs and wages and rises in disability and family breakdown. The people who gained from cheaper goods were spread across the country; the people who lost were concentrated in specific places, and they noticed.

By the 2010s a backlash was growing on both the political left and right. Critics argued that trade deals served corporations, that workers in poor countries were exploited, and that a country that made nothing was not safe. Defenders replied that closing borders would raise prices, cost more jobs than it saved, and hurt the poorest countries most. Both sides had evidence. In 2018 the United States began imposing new tariffs on China and China answered in kind, and the COVID pandemic of 2020 showed how fragile long supply chains could be when a single factory closed. The question of how open the world’s economy should be is not settled, and your generation will help decide it.

When Mao died in 1976, China was poor. Most of its people were peasants, and a bad harvest still meant hunger. Its new leader, Deng Xiaoping, had been purged twice under Mao and had no interest in repeating his experiments. In 1978 he began to let farmers sell what they grew above a quota, and harvests jumped. He opened special economic zones on the coast, starting with a fishing town called Shenzhen, where foreign companies could build factories with cheap labor and low taxes. Deng’s slogan was that it did not matter whether a cat was black or white as long as it caught mice. Shenzhen is now a city of more than twelve million.

The results were the fastest sustained growth any large country has recorded. For three decades China’s economy grew close to ten percent a year, doubling roughly every seven years. It joined the World Trade Organization in 2001, and its exports flooded the world. By 2010 it had passed Japan to become the second-largest economy on Earth. About eight hundred million Chinese people escaped extreme poverty, by the World Bank’s count, the largest such change in history. Cities of skyscrapers rose where rice fields had been. China built more high-speed rail in fifteen years than the rest of the world combined.

Growth did not bring democracy. The Communist Party kept its monopoly on power, as it had shown at Tiananmen in 1989. It censors the internet, jails critics, and has held perhaps a million Uyghur Muslims in camps in the western region of Xinjiang, which the government calls vocational training and human rights groups and several governments call mass detention. The party’s bargain with its people was prosperity in exchange for obedience. For many years, with incomes rising, most accepted it. Whether the bargain holds as growth slows and the population ages is one of the great open questions of your lifetime.

China’s rise changed the world’s map of power. It is the largest trading partner of most countries on Earth, including many in Africa and Latin America, where it builds ports, railroads and stadiums in exchange for resources and influence. It has built a large navy and claims most of the South China Sea. The United States, which welcomed China into the world economy hoping trade would make it more open, now treats it as its chief rival. Whether the two will compete, cooperate or collide is a question American and Chinese students will inherit. Illinois soybeans, Boeing planes and Caterpillar machines, all sold to China, are one measure of what is at stake.

In 1951, six years after the war, France, West Germany, Italy and three small neighbors agreed to run their coal and steel industries jointly. The idea, pushed by the French planner Jean Monnet, was that countries whose steel was shared could not build tanks to fight each other. The community grew into a common market with no tariffs among its members. In 1992 the members signed a treaty at Maastricht creating the European Union, with a shared citizenship, plans for a single currency and a promise to act together on foreign policy. Border checks between most members disappeared. A German could drive to Spain without showing a passport.

In 2002 twelve countries replaced their francs, marks and lire with the euro, the first time major nations had given up their own money for a shared one. In 2004 ten more countries, most of them former Soviet satellites, joined the Union, and Poland, Hungary and the Baltic states that had escaped the iron curtain in 1989 became full members of the West. By the 2010s the EU had twenty-eight members and about five hundred million people, the largest economy in the world by some measures, with a parliament, a court and rules that governed everything from phone charges to the shape of bananas.

Then the strains showed. A shared currency meant Greece and Germany had the same money but very different economies, and when Greece could not pay its debts after 2009, Germans resented paying to rescue it while Greeks resented the cuts demanded in return. When more than a million refugees arrived in 2015, mostly from the Syrian war, countries argued bitterly over who should take them. Many citizens felt that decisions were being made in Brussels by people they had never voted for. In June 2016 British voters chose, by fifty-two to forty-eight percent, to leave. Britain left in January 2020, the first member ever to do so.

The EU today has twenty-seven members and a hard question at its center. Its founders believed that sharing sovereignty, a country’s right to make its own decisions, was the price of peace and prosperity. Its critics believe that a democracy has to be small enough for citizens to control it. Russia’s full invasion of Ukraine in 2022 pushed the members closer together again, and Ukraine itself asked to join. The Union has kept its members from fighting one another for seventy years, which no earlier arrangement in Europe ever managed. Whether it can also make decisions its citizens accept is still being tested.

On the morning of September 11, 2001, nineteen men hijacked four airliners. They flew two into the twin towers of the World Trade Center in New York, one into the Pentagon near Washington, and the fourth, after passengers fought back, crashed in a Pennsylvania field. Nearly three thousand people were killed, more than in any attack on American soil. The hijackers belonged to al-Qaeda, a network led by Osama bin Laden, a wealthy Saudi who had fought the Soviets in Afghanistan and now called for war against the United States. He was sheltered by the Taliban, the extremist group ruling most of Afghanistan.

Terrorism means using violence against civilians to spread fear for a political goal. It is a tactic, not a country, and that made the response hard to define. In October 2001 the United States and its allies invaded Afghanistan, drove out the Taliban within weeks, and began trying to build a new government. In March 2003 the United States invaded Iraq, arguing that its dictator, Saddam Hussein, had weapons of mass destruction and ties to terrorists. No such weapons were found, and the claimed ties proved false. Saddam was overthrown, but Iraq fell into years of civil war among religious and ethnic groups, in which American troops were caught.

The wars lasted far longer than anyone planned. The Iraq war killed about forty-five hundred American troops and an estimated hundreds of thousands of Iraqis. The chaos in Iraq and Syria produced the Islamic State, or ISIS, which seized a territory the size of Britain in 2014 and was broken by 2019. In Afghanistan the Taliban never went away, and after twenty years, in August 2021, the last American troops left and the Taliban retook the country within days. About twenty-four hundred Americans and far larger numbers of Afghans had died there. Illinois National Guard units served in both wars, and the names of the state’s dead are recorded in Springfield.

The wars changed life at home. A new Department of Homeland Security was created. Airport searches, which barely existed before 2001, became routine. Laws expanded the government’s power to watch communications, and prisoners were held for years without trial at a naval base in Cuba. Americans argued, and still argue, about the balance between safety and freedom, and about whether the wars made the country safer or created new enemies. Historians will judge with more evidence than we have. What is already clear is that a single morning redirected two decades of American power and cost trillions of dollars.

Roughly one person in thirty on Earth lives in a country other than the one where he or she was born, about two hundred and eighty million people. Most are migrants who moved by choice, for work, study or family. A smaller group are refugees: people who fled war or persecution and cannot safely go home. The 1951 Refugee Convention, written after the war had made millions of Europeans homeless, promised that no country would send a refugee back to a place where his or her life was in danger. Most countries signed it. Living up to it has been harder.

The numbers have grown. Syria’s civil war, which began in 2011, drove more than half the country’s people from their homes; millions crossed into Turkey, Lebanon and Jordan, and in 2015 more than a million reached Europe, many on flimsy boats across the Mediterranean. Wars and hunger in Afghanistan, Sudan, Venezuela and elsewhere added more. Russia’s invasion of Ukraine in 2022 sent millions west within weeks. By the United Nations count, more than one hundred million people were forcibly displaced from their homes in 2022, the most ever recorded. Most refugees are hosted not by rich countries but by poor neighbors of the country they fled.

Migration divides people because it involves real trade-offs. Migrants fill jobs, pay taxes, start businesses and send money home that supports whole villages; economists find that over time they add more to a country than they cost. Yet a sudden arrival can strain schools, housing and hospitals in one town while the benefits spread across the whole economy. Some citizens fear losing jobs or the culture they grew up in. Some governments have built fences and deported people; others have welcomed them. Every wealthy democracy has argued over it, and the arguments have reshaped elections in Europe and the United States.

Chicago has been a city of migrants since it was founded. Poles, Germans, Irish, Italians and Jews in the 1800s; Black families from the South in the Great Migration; Mexicans through the whole twentieth century; and more recently Indians, Chinese, Filipinos and Ukrainians. About one in five Chicagoans was born in another country. In 2022 and 2023 tens of thousands of asylum seekers, mostly from Venezuela, were bused to Chicago from the southern border, and the city struggled to shelter them. The debate you hear in the news is the same one this lesson describes, happening in your own neighborhood.

For most of history, what a ruler did inside his own borders was nobody else’s business. The Holocaust broke that idea. At Nuremberg in 1945 and 1946, the Allies put Nazi leaders on trial for crimes against humanity and established that following orders was no defense. In December 1948 the United Nations adopted the Universal Declaration of Human Rights, drafted by a committee chaired by Eleanor Roosevelt. It listed rights every person holds simply by being human: life, liberty, fair trials, free speech, free worship, education, and freedom from torture and slavery. It was a statement of principle, not a law, but it gave every movement for rights since a text to point to.

Treaties followed. The 1948 Genocide Convention made the deliberate destruction of a people a crime under international law. The Geneva Conventions of 1949 set rules for war: prisoners must be fed and protected, the wounded cared for, civilians spared. Since then, treaties have banned torture, protected children, and asserted the rights of women. By signing, governments accepted that others could judge them. Whether they lived up to their signatures was another matter. The Cold War superpowers each pointed at the other’s abuses and shielded their own allies.

The 1990s tested the system and it mostly failed. In Rwanda in 1994, extremists among the Hutu majority murdered about eight hundred thousand Tutsi and moderate Hutu in about one hundred days, with machetes and radio broadcasts, while UN peacekeepers on the ground were ordered not to intervene and the world argued over the word genocide. In Bosnia in 1995, Serb forces killed about eight thousand Muslim men and boys at Srebrenica, a town the UN had declared a safe area. Afterward, courts were created to try the killers, and in 2002 a permanent International Criminal Court opened at The Hague to prosecute genocide, war crimes and crimes against humanity when national courts will not.

The court has convicted a handful of warlords and indicted heads of state. But it has no police force, and the United States, China, Russia and India have not joined it, fearing that their own soldiers or leaders could be charged. Human rights law thus lives in tension: it claims that some acts are crimes everywhere, but it depends on governments to enforce it against themselves. Still, the words matter. A prisoner in a cell, a woman denied school, a worker in a locked factory can all say that the world has agreed their treatment is wrong. In 1900 they could not.

In 1958 a scientist named Charles Keeling began measuring carbon dioxide in the air on top of a volcano in Hawaii, far from any city. The line he drew has climbed every year since. In 1960 the air held about three hundred and seventeen parts of carbon dioxide per million. By 2020 it held about four hundred and fourteen, higher than at any time in at least eight hundred thousand years, as air bubbles trapped in ancient ice show. The cause is not in doubt: burning coal, oil and gas releases carbon that had been buried for millions of years. Carbon dioxide traps heat, as scientists have known since the 1800s. More of it means a warmer planet.

The Earth has warmed about 1.2 degrees Celsius, roughly 2 degrees Fahrenheit, since the late 1800s. That sounds small. It is enough to melt glaciers, raise sea levels, and make heat waves, droughts, wildfires and heavy rains more common. Illinois has seen it: the state’s winters have warmed faster than its summers, and the very heavy rains that flood Chicago basements come more often than they did fifty years ago. Farmers in the state plant earlier and face wetter springs. Effects fall hardest on the poor, in Illinois and in the world, because they have the fewest ways to move, rebuild or cool off.

The problem is global in a way that makes it fiendishly hard. Carbon dioxide from a power plant in Ohio or a factory in China mixes into the same air. A country that cuts its own emissions pays the cost while everyone shares the benefit, so each has a reason to wait for the others. Countries that industrialized early, led by the United States, put most of the carbon now in the air there; countries industrializing now, led by China and India, emit the most today and argue that they deserve the same chance to grow. In 2015, in Paris, nearly every country agreed to set its own targets and try to keep warming well below two degrees. The targets so far are not enough to meet that goal.

What to do about it is a political argument, and the evidence bears on it without settling it. Solar and wind power have become the cheapest new electricity in much of the world, and electric cars are spreading, which means cutting emissions costs less than it once did. But coal still powers much of Asia, and oil fuels nearly every ship and plane. People disagree about how fast to change, who should pay, and how much to trust governments to manage it. Those are questions about values as well as facts. The facts, though, are the starting point, and the Keeling curve is still climbing.

In the fall of 1918, as World War I ended, a new strain of influenza spread along the routes soldiers traveled. It killed about fifty million people worldwide, more than the war itself, most of them young adults. In Chicago, theaters and dance halls were closed and funerals were limited to ten people. There were no vaccines, no antibiotics for the pneumonia that followed, and no way to see the virus, which was too small for the microscopes of the day. Cities that closed schools and gatherings early and kept them closed had fewer deaths, a lesson public health officials remembered a century later.

The twentieth century then won a series of victories. Vaccines defeated polio, which had paralyzed thousands of American children each summer. A worldwide campaign led by the World Health Organization tracked down every case of smallpox, a disease that had killed hundreds of millions, and in 1980 declared it gone from the Earth, the only human disease ever wiped out. Then in 1981 doctors in Los Angeles and New York reported a new illness that destroyed the body’s defenses. HIV, the virus that causes AIDS, has since killed about forty million people, most in Africa. Drugs that keep it in check exist, and the fight to get them to everyone who needs them continues.

In late 2019 a new virus appeared in the Chinese city of Wuhan. By March 2020 it was on every continent, and the World Health Organization declared COVID-19 a pandemic. Air travel had carried it around the world in weeks. Governments closed borders, schools and businesses. Streets in Chicago emptied. Scientists sequenced the virus’s genes within days of its discovery and shared them online, and vaccines were developed and tested in under a year, a speed never before achieved. The reported death toll passed seven million; most experts believe the true number is far higher because many deaths were never counted.

The pandemic revealed the connected world at its best and worst. Data flowed freely among scientists, and manufacturers on three continents made billions of vaccine doses. But rich countries bought most of them first, and poor countries waited. Supply chains for masks and medicines snapped. False claims about the virus and the vaccines spread online faster than corrections. Trust in governments and experts fell in many countries. The next lesson turns to the question this raised for everyone: in a world of instant information, how do you decide what to believe?

Two things are true at once. Between countries, the gap has narrowed: China, India and much of Asia have grown far faster than Europe and the United States, so the average person in a poor country is closer to the average person in a rich one than in 1990. Within countries, in many places, the gap has widened. In the United States the share of income going to the top one percent of earners roughly doubled between 1980 and the 2010s, according to standard studies, while the wages of workers without a college degree barely rose after adjusting for prices. A similar story, in different degrees, played out in Britain, China, India and Russia.

Why? Economists point to several causes working together. Technology rewarded people with skills that computers made more valuable and replaced people whose work computers could do. Trade moved factory jobs to lower-wage countries. Unions, which had once pushed wages up for millions, shrank. Tax rates on high incomes fell in many countries after 1980. The rewards for owning things, such as stocks, companies and buildings, grew faster than the rewards for working. Which of these matters most is argued, and the answer differs by country. What is not argued is the pattern.

The gap is visible in Illinois. Chicago’s Loop and North Side have some of the highest incomes in the nation, while neighborhoods a few miles south and west have lost factories, stores and population for fifty years. Life expectancy in the wealthiest Chicago neighborhoods runs about thirty years longer than in the poorest, one of the largest such gaps in any American city. Downstate towns that lost a plant to Mexico or to automation have seen young people leave. These are not abstractions to the people living them, and they shape how people vote.

Inequality raises questions that evidence can inform but not settle. Does a large gap slow growth, or does the chance of great wealth drive it? Does it undermine democracy when the rich can fund campaigns and the poor drop out of voting? What should be done: higher taxes on wealth, stronger unions, better schools, a minimum income, or nothing beyond letting markets work? Reasonable people disagree, and every one of these positions has serious economists and voters behind it. A citizen’s job is to know the facts, weigh the trade-offs, and decide, rather than accept the first slogan that fits.

In 1980 most Americans got their news from one of three television networks and a local newspaper, and those outlets decided what counted as news. Today a story reaches you through a feed built by software that chooses what to show you based on what you clicked before. The software, called an algorithm, is not trying to inform you. It is trying to keep you watching, because time on the screen is what the company sells to advertisers. Stories that make you angry, afraid or amused keep you watching longer than stories that are merely true and important. That is not a conspiracy. It is a business model, and it shapes what billions of people see every day.

Behind every story is a source: the person or record where the information came from. A good reporter names sources, quotes documents and lets you check. A weak story says experts believe or people are saying. Ask who is speaking and how they know. A doctor describing a disease she treats, a government office publishing its own count, and a stranger on a video repeating something a friend told him are not equal, even if the video is more exciting. Ask also who benefits. A story about a miracle cure posted by the company selling it is not the same as one from a hospital.

Every news source has a point of view, and that is not the same as lying. A newspaper owned by a business group, a broadcaster funded by a government, and a site run by an activist will choose different stories and different words for the same event. A refugee crisis in one outlet is a migrant invasion in another. The word bias describes this tilt. The cure is not to find the one unbiased source, which does not exist, but to read across sources with different tilts and notice where they agree. When a right-leaning and a left-leaning outlet report the same facts, those facts are probably solid. Where they differ is where you need to look harder.

The historians’ habits taught in this course are the same habits a citizen needs. Who made this? When? Why? What did they leave out? Who else was there, and what would they say? A photograph from a war may be real but from a different war. A quote may be real but cut off before the sentence that changes its meaning. A number may be real but chosen from a range to make one case. None of that is new. What is new is the speed and the volume, and the fact that you, not an editor, are now the one deciding what to pass on.

Misinformation is false information spread by people who believe it. Disinformation is false information spread on purpose to deceive, often by governments or groups with a goal. Both spread faster than truth: a study of millions of posts found that false stories traveled farther and faster than true ones, mostly because they were more surprising. Governments including Russia’s have run operations that create fake accounts posing as ordinary Americans to inflame arguments on both sides of an issue. The goal is not always to make you believe something false. Sometimes it is to make you believe nothing at all.

The first habit is to pause. Strong feeling is the signal to slow down. If a story makes you furious or thrilled, that is exactly when you are easiest to fool, and exactly when a false story is designed to be shared. The second habit is lateral reading: instead of studying the page in front of you, open new tabs and find out what other sources say about the site and the claim. Professional fact-checkers do this and outperform professors and students who stay on the page. A site’s own About page tells you what it wants you to think of it. Other sites tell you what it is.

The third habit is to trace a claim to its origin. A statistic in a post came from somewhere: a study, a report, a count. Find it. Often the original says something narrower than the post, or says the opposite, or does not exist. A photograph can be checked by searching for the image to see where else it has appeared and when. A quote can be searched to see whether the person said it, and what came before and after. This takes minutes, and it is the difference between knowing and repeating.

The last habit is the hardest. Ask yourself what evidence would change your mind, and go look for it. People are very good at finding reasons to believe what they already believe, and the feed is very good at supplying them. A citizen who cannot name what would change his or her mind is not reasoning but rooting. This course has shown you how historians argue from evidence about slavery, war, revolution and empire. You now live in a world that generates more evidence, and more noise, in a day than those historians saw in a lifetime. The habits are the same. The stakes are yours.