World Wars: When America Stopped Being Separate from the World
1914-1945 · WY SS12.4.5 global conflict + economic crisis
Anne Frank · The Diary of a Young Girl · 1944
"In spite of everything,
I still believe that people
are really good at heart."
— Anne Frank was 14 when she wrote this — your exact age. She was hiding from the Nazis in an attic in Amsterdam. She died at 15 in a concentration camp. Her father survived and published her diary.
WWI (1914-1918) dragged America in late but changed everything. The 1920s roared, then the stock market crashed in 1929, starting the Great Depression. FDR's New Deal rebuilt the country. WWII (1939-1945) ended the Depression, defeated fascism, brought women into the workforce, and made America a superpower — but also included internment of Japanese Americans, atomic bombs on Hiroshima and Nagasaki, and the Holocaust.
primary source
FDR's First Inaugural Address
"So, first of all, let me assert my firm belief that the only thing we have to fear is fear itself — nameless, unreasoning, unjustified terror which paralyzes needed efforts to convert retreat into advance."
— Franklin D. Roosevelt · March 4, 1933 · Public Domain FDR took office in the worst year of the Great Depression. About 25% of Americans were unemployed. He had 100 days to convince the country it would survive.
Pick how you want to learn this
All three teach the same period from a different angle.
For most of its history, America had stayed out of European wars. Geography helped — two big oceans on either side. But in the 20th century, that distance stopped working. The world got smaller (telephones, planes, faster ships), and what happened across the ocean started mattering at home.
World War I (1914–1918). It started in Europe with a tangled web of alliances after Archduke Franz Ferdinand of Austria-Hungary was assassinated in Sarajevo. Within weeks, Germany, Austria-Hungary, and the Ottoman Empire (the Central Powers) were at war with Britain, France, and Russia (the Allies). Soldiers fought in trenches for years, using machine guns, poison gas, and tanks. About 17 million people died.
America stayed out for almost 3 years. Then in 1917, German submarines started sinking American ships, and Germany sent a secret telegram (the Zimmermann Telegram) trying to convince Mexico to attack the U.S. America declared war. American troops helped break the stalemate, and Germany surrendered in November 1918.
1914WWI starts in Europe.
1917U.S. enters WWI.
1918WWI ends. Worldwide flu pandemic kills about 50 million.
1929October — stock market crashes. Great Depression begins.
1933FDR inaugurated. New Deal begins.
1939WWII starts in Europe (Germany invades Poland).
1941December 7 — Japan attacks Pearl Harbor. U.S. enters WWII the next day.
1944D-Day — Allied invasion of France.
1945Germany surrenders (May). Atomic bombs on Hiroshima and Nagasaki (August). Japan surrenders (September). WWII ends.
The 1920s ("Roaring Twenties"). After WWI, the U.S. economy boomed. Jazz exploded out of Black neighborhoods in New Orleans, Chicago, and Harlem. The Harlem Renaissance made Langston Hughes, Zora Neale Hurston, Duke Ellington, and Louis Armstrong into household names. Women got the vote (1920), cut their hair short (flappers), and rebelled against older rules. Cars, radios, and movies became everyday things.
The Great Depression (1929–1939). On October 29, 1929 (Black Tuesday), the stock market crashed. The economy unraveled. Banks failed, taking people's savings with them. By 1933, about 1 in 4 American workers had no job. Farmers in the Midwest got hit by both the economic crash AND the Dust Bowl — a massive drought that turned topsoil to dust storms.
President Franklin D. Roosevelt (FDR) took office in 1933. His New Deal was a flood of new federal programs — jobs, dams, electricity for rural areas, Social Security, bank insurance, labor protections. Some of it worked. Some of it didn't. But it changed forever what Americans expected the federal government to do.
🎙️"Fireside chats." FDR spoke directly to Americans through their radios in calm, informal speeches. He called them fireside chats. He didn't lecture; he explained. For a country that had been told for years that the government couldn't help them, hearing the President speak like a neighbor was huge. It rebuilt trust.
World War II (1939–1945). Adolf Hitler and the Nazi Party rose to power in Germany. They scapegoated Jewish people, communists, disabled people, Roma people, and others for Germany's problems. By 1939 Hitler had invaded Poland. Britain and France declared war. Japan was already at war with China; in 1940 it joined Germany and Italy as the Axis Powers.
America stayed out — again — until December 7, 1941, when Japan attacked the U.S. naval base at Pearl Harbor, Hawaii. About 2,400 Americans died in a few hours. The next day, FDR asked Congress for a declaration of war ("a date which will live in infamy"). The U.S. fought in both Europe and the Pacific simultaneously for almost 4 years.
WWII brought women into factories in huge numbers — the Rosie the Riveter image came from that. It pulled the country fully out of the Depression. It ended with America as one of two world superpowers (the other being the Soviet Union). And it ended in August 1945 when the U.S. dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki, killing about 200,000 people, most of them civilians.
Two months after the war ended, the United Nations was founded. The idea: never let this happen again. We're still finding out whether it'll work.
This whole 30-year stretch is one long chain reaction. Each event sets up the next. Here's the chain:
WWI ends (1918) → The Treaty of Versailles punishes Germany with massive war debts and lost territory. Germany's economy collapses. → This humiliation sets up Hitler's rise.
The 1920s boom → Americans buy stocks on credit (borrowed money). Banks lend recklessly. Inequality is huge. → The system is fragile.
Stock market crashes (1929) → Banks fail. People lose savings. Unemployment hits 25%. → The Great Depression.
The Depression spreads worldwide → Germany suffers most because its economy was already broken. → Hitler campaigns on blaming Jewish people and "outsiders" for Germany's problems. He wins power in 1933.
Hitler rebuilds Germany's military (violating the Versailles treaty) and starts invading neighbors. → Britain and France try to appease him. It doesn't work. → He invades Poland in 1939. WWII begins.
Japan, meanwhile, is invading China and Southeast Asia, wanting an empire. The U.S. cuts off oil exports to Japan in protest. → Japan attacks Pearl Harbor in 1941 to knock out the U.S. Pacific fleet. → The U.S. enters the war.
U.S. industry mobilizes for war → Factories that made cars now make tanks. Women fill jobs men left behind. Unemployment vanishes. → The Great Depression ends, killed by wartime production.
Allied victory (1945) → America emerges as one of two superpowers. → The Cold War with the Soviet Union begins almost immediately. (You'll see that in Unit 6.)
The big pattern: Economic pain → political extremism → war → economic recovery → new geopolitical map. That pattern wasn't unique to this era — historians watch for it every time there's a recession or a crisis. It's why economists pay attention to inequality and why political scientists pay attention to scapegoating.
One specific cause→effect inside the Depression:
Cause: No federal deposit insurance. → Bank panics. People rush to withdraw money. Banks collapse.
FDR's fix: Created the FDIC (Federal Deposit Insurance Corporation) in 1933. Today every bank account up to $250,000 is federally insured. → No widespread bank panics since then.
That's how policy from 90 years ago is still keeping your bank account safe right now.
This unit has three parts that are genuinely hard to hold. Historians don't skip them; they teach them honestly. We will too.
Japanese-American Internment (1942–1945).
After Pearl Harbor, FDR signed Executive Order 9066 in February 1942. It authorized the U.S. military to forcibly relocate about 120,000 people of Japanese ancestry — most of them American citizens born in the U.S. — into prison camps. They had days to sell their homes, businesses, and possessions, often at a tiny fraction of their value.
One of those camps, Heart Mountain, was in Wyoming. About 14,000 people were imprisoned there between 1942 and 1945. Today there's a memorial and a museum at the site. You can visit it.
"I am proud that I am an American of Japanese ancestry. I believe in this nation's institutions, ideals, and traditions; I glory in its heritage; I boast of its history… But it is also true that I am the victim of the worst type of racial discrimination." — Fred Korematsu, who refused to go to a camp and was arrested.
Fred Korematsu's case went to the Supreme Court. In 1944, the Court ruled the internment was legal (Korematsu v. United States). Forty years later, that decision was officially repudiated as one of the worst in Supreme Court history. In 1988, President Reagan signed a law apologizing and giving each surviving internee $20,000.
It is a fact of American history: the U.S. government imprisoned U.S. citizens based purely on race, with no charges, no trials, and no evidence of disloyalty. Germany was the enemy in Europe but German-Americans weren't imprisoned. Italy was an Axis power but Italian-Americans weren't imprisoned. Only Japanese-Americans.
The Holocaust.
While America was fighting WWII abroad, Nazi Germany was systematically murdering Jewish people across Europe. By 1945, the Nazis had killed about 6 million Jewish people — including about 1.5 million children — and roughly 5 million others (Roma, disabled people, gay people, political prisoners, Soviet POWs).
This is what the word genocide was coined to describe — the deliberate, organized killing of an entire group of people because of who they are.
It was not a secret. The U.S. government knew Jewish people were being killed by at least 1942. Yet the U.S. turned away ships of Jewish refugees (the SS St. Louis, 1939, was the most famous — many of its passengers later died in concentration camps). Antisemitism in America was real and helped delay action.
Anne Frank's diary is one of the most-read books in the world for a reason. She was 13 when she started writing it. She was your age — 14 — for most of it. She died at 15 in Bergen-Belsen, weeks before British troops liberated the camp. Her father, the only one in their family to survive, published her words after the war.
"How wonderful it is that nobody need wait a single moment before starting to improve the world." — Anne Frank
The Atomic Bombs.
On August 6, 1945, the U.S. dropped an atomic bomb on the Japanese city of Hiroshima. About 80,000 people died instantly. Many more died over weeks and years from radiation poisoning. Three days later, on August 9, the U.S. dropped a second bomb on Nagasaki, killing about 40,000 instantly.
Japan surrendered six days later. WWII was over.
Historians still debate this decision, and they probably always will. The arguments for: the alternative — a U.S. invasion of Japan — was projected to cost hundreds of thousands more American lives and possibly millions of Japanese lives. The arguments against: Japan was already close to surrender, civilians were the target, and the U.S. used a weapon so powerful it created a new kind of warfare humanity has been afraid of ever since.
Both arguments are taken seriously. The civilians who died — most of them women, children, and elderly people who had no military role — are real, and they matter. The American soldiers who would have died in an invasion are also real. Sometimes history is two terrible things at once and you have to look at both.
🎬Pop-culture anchors:Saving Private Ryan (1998, Spielberg) shows the D-Day landing realistically — and is famously hard to watch for veterans. Schindler's List (1993) tells the story of a German businessman who saved over 1,000 Jewish workers during the Holocaust. Grave of the Fireflies (1988) shows WWII from the perspective of Japanese children. Hidden Figures covers the WWII-era beginnings of Black women in NASA. All of these are honest about how bad the war was, and they're worth your time.
why we hold this
These three things — internment, the Holocaust, the bombs — sit together in history because they all show the same pattern: in a war, governments do things they would never normally do, and ordinary people pay the price. The lesson isn't "America bad" or "America good." The lesson is: pay attention. Hard things happen when fear and power combine. Knowing the history is how you recognize when it's happening again.
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tutor ask anything · wars, Depression, hard history
Hey 💛 this unit holds some of the hardest parts of the 20th century — two world wars, the Depression, the Holocaust, internment, the atomic bombs. We can talk about any of it. We can take it slow. Ask whatever you're wondering, even if it feels too big.