World War II and the Postwar World
World War II is the hinge of the twentieth century. It killed more people than any conflict in history, ended the Depression in the United States, and left two superpowers standing where a half-dozen empires had been. Almost everything on the second half of a social studies timeline runs through it.
World War II began in Europe in 1939 when Germany invaded Poland, and the United States entered after Japan attacked Pearl Harbor on December 7, 1941. The Allies defeated Germany in May 1945 and Japan in September 1945. The war reshaped the world order, creating the United Nations, a rebuilt Western Europe, and a rivalry between the United States and the Soviet Union.
How the war began
The peace after World War I proved fragile. Germany’s economy collapsed under debt and depression, and Adolf Hitler’s Nazi Party took power in 1933 promising national revival and blaming Jews and others for Germany’s humiliation. Aggressive expansion followed, and Britain and France initially responded with appeasement, hoping concessions would satisfy Hitler.
They did not. Germany invaded Poland on September 1, 1939, and Britain and France declared war. Japan, meanwhile, had been expanding in Asia since its invasion of Manchuria in 1931.
The United States again stayed out at first, though it supplied the Allies through Lend-Lease. That ended on December 7, 1941, when Japan attacked the American naval base at Pearl Harbor. Congress declared war the next day.
The home front
The war transformed daily American life. Factories converted to war production, and the resulting demand finally ended the unemployment of the Depression. With millions of men in uniform, women entered industrial jobs in unprecedented numbers, an effort symbolized by the “Rosie the Riveter” image. Civilians dealt with rationing of gasoline, rubber, sugar, and meat, and bought war bonds.
The home front also produced one of the era’s clearest injustices. Executive Order 9066, signed in 1942, led to the forced removal and incarceration of roughly 120,000 people of Japanese ancestry, most of them American citizens, in camps far from the coast. No comparable action was taken against German or Italian Americans as a group. Decades later the federal government formally apologized and paid reparations. This is often paired with the language of civil liberties, asking what rights were suspended and on what grounds.
Turning points and the end of the war
In Europe, the Allied invasion of Normandy on June 6, 1944, known as D-Day, opened a western front and began the drive into Germany. Germany surrendered on May 8, 1945, celebrated as V-E Day.
In the Pacific, the United States advanced island by island toward Japan. In August 1945 the United States dropped atomic bombs on Hiroshima on August 6 and Nagasaki on August 9. Japan announced its surrender days later, and the formal signing took place on September 2, 1945. Whether the bombings were necessary to end the war without an invasion remains one of the most debated questions in modern history, and the useful skill is identifying the arguments rather than declaring a winner.
As Allied forces advanced, they uncovered the full scale of the Holocaust, the systematic murder of about six million Jews along with millions of Roma, disabled people, political prisoners, and others. The evidence gathered shaped postwar law, including the Nuremberg trials and the concept of crimes against humanity.
Building the postwar world
The victors tried to build institutions that would prevent a repeat. The United Nations was founded in 1945, this time with American membership. Economic agreements reached at Bretton Woods in 1944 created a framework for international finance.
| Postwar action | Year | Purpose |
|---|---|---|
| United Nations founded | 1945 | International cooperation and security |
| Marshall Plan | 1948 | American aid to rebuild Western Europe |
| NATO formed | 1949 | Mutual defense alliance |
At home, the GI Bill of 1944 sent millions of veterans to college and helped them buy homes, fueling suburban growth and a long postwar boom. The baby boom followed. But the alliance with the Soviet Union, always a marriage of convenience against a common enemy, broke down quickly, and the Cold War began.
Watch: A Short Video Lesson
CrashCourse covers this ground clearly in a few minutes. It pairs well with the reading above:
Practice
1. The United States entered World War II directly as a result of
- the invasion of Poland
- the attack on Pearl Harbor
- the Marshall Plan
- D-Day
2. The Marshall Plan was designed to
- rebuild Western European economies after the war
- create the United Nations
- relocate Japanese Americans
- end rationing in the United States
3. A historian argues that World War II, not the New Deal, ended the Depression. Which evidence best supports this?
- The GI Bill passed in 1944
- Unemployment fell sharply as war production expanded after 1941
- The United Nations was founded in 1945
- Rationing was unpopular
Answers: 1. B. 2. A. 3. B — the employment change tied to war production is the evidence that speaks to the claim.
Where this fits
The alliances and rivalries formed in 1945 set the terms for the next forty-five years, covered in Cold War, decolonization, civil rights, and recent history. The war’s economic story picks up from the Great Depression and New Deal. See all lessons on the Social Studies hub.
Recommended Prep Books
These study guides can help you keep your momentum going:
Related to This Article
More math articles
- Grade 2 Math Practice for Arkansas Second Graders
- Shelf Life, FIFO, Storage, and Locator Systems
- Grade 6 Informational Reading: Central Idea, Claims, and Text Structure Strategies
- Understanding Triangles: A Comprehensive Guide to Their Classification and Properties
- Plant Structures and Their Jobs
- The Great Math Tour: Exploring the World of Circle Graphs
- The Best Grade 3 Math Book for Georgia Students
- How to Measure Angles with a Protractor
- Maine Through Year Assessment Grade 8 Math Free Worksheets: Printable Grade 8 Math Practice for Every Skill
- Top 10 6th Grade Common Core Math Practice Questions
What people say about "World War II and the Postwar World Explained"?
No one replied yet.