World War 2 and American Involvement

USII.14 Explain the strength of American isolationism after World War I and analyze its impact on U.S. foreign policy. (H)
USII.15 Analyze how German aggression in Europe and Japanese aggression in Asia contributed to the start of World War II and summarize the major battles and events of the war. On a map of the world, locate the Allied powers (Britain, France, the Soviet Union, and the United States) and Axis powers (Germany, Italy, and Japan). (H)
  1. a. Fascism in Germany and Italy
  2. b. German rearmament and militarization of the Rhineland
  3. c. Germany’s seizure of Austria and Czechoslovakia and Germany’s invasion of Poland
  4. d. Japan’s invasion of China and the Rape of Nanking
  5. e. Pearl Harbor, Midway, D-Day, Okinawa, the Battle of the Bulge, Iwo Jima, and the Yalta and Potsdam conferences
  6. Seminal Primary Documents to Read: President Franklin Roosevelt, “Four Freedoms,” speech (1941)
  7. Seminal Primary Documents to Consider: Justice Robert M. Jackson’s opinion for the Supreme Court in West Virginia State Board of Education v. Barnette (1943) and Learned Hand’s The Spirit of Liberty (1944)
USII.16 Explain the reasons for the dropping of atom bombs on Japan and their short and long-term effects. (H)
USII.17 Explain important domestic events that took place during the war. (H, E)
  1. a. how war-inspired economic growth ended the Great Depression
  2. b. Philip Randolph and the efforts to eliminate employment discrimination the entry of large numbers of women into the workforce
  3. c. the internment of West Coast Japanese-Americans in the U.S. and Canada
Maps and Political Cartoons from WW2


  • No war in history killed more people or destroyed more property than World War II. Seventeen million combatants--and an unknown number of civilians--lost their lives in the conflict. Altogether, 70 million people served in the armed forces during the war; of these, some 7.5 million Soviet troops died in World War II, along with 3.5 million Germans, 1.25 million Japanese, and 400,000 Americans. Civilian deaths were even higher. At least 19 million Soviet civilians, 10 million Chinese, and 6 million European Jews lost their lives during the war.
WW2 Timeline

Events Leading to War

  • Japan, Italy, and Germany all committed warlike acts in the 1930s. In 1931 Japan began an invasion of China. Italy, led by Benito Mussolini’s Fascist Party, conquered the East African country of Ethiopia in 1935.
  • Germany was the biggest threat to world peace. Adolf Hitler and his National Socialist, or Nazi, Party wanted Germans to rule over everyone else. In March 1938 German troops marched into Austria.
  • Hitler next wanted a part of Czechoslovakia where German-speaking people lived. Great Britain and France agreed to let him have it. They hoped to satisfy Hitler so that he would make no more demands. Their plan—called appeasement—was a failure. Within six months Germany took control of all of Czechoslovakia.
  • Hitler then planned to take over Poland. Britain and France promised to help Poland in case Germany attacked it. Germany prepared for war by making peace with the Soviet Union (which was not yet on the Allies’ side) in August 1939. Germany did not want to fight Britain, France, and the Soviet Union all at the same time.
Black soldiers during Inspection

War with Germany Begins

From left to right-Winston Churchill, Franklin Roosevelt, Joseph Stalin-The Allies


  • On September 1, 1939, Germany invaded Poland. This began World War II. The Germans used a new kind of attack. They called it blitzkrieg, or “lightning war.” Blitzkrieg relied on fast-moving tanks and warplanes to shock the enemy into surrendering.
  • After this invasion, Britain and France declared war on Germany. Australia, New Zealand, Canada, India, and South Africa joined Britain on the side of the Allies. But no one could help when the Soviet Union attacked Poland on September 17. Germany and the Soviet Union divided Poland between them. The Soviet Union also invaded Latvia, Lithuania, Estonia, and Finland during 1939.

Scandinavia and the Low Countries

  • Between April and June 1940 the Germans took over Norway and Denmark. In May they moved into the Low Countries—Belgium, the Netherlands, and Luxembourg.


  • In mid-May 1940 the first German troops crossed into France. By June 14 the Germans had entered Paris, the French capital.
  • On June 22 France agreed to let Germans rule most of their country. However, many French people continued to fight the Germans. They were called the Free French. They took orders from Charles de Gaulle. De Gaulle’s headquarters were in Britain.
  • As France was falling to the Germans, Italy declared war against France and Britain. On June 10, 1940, Italy entered the war as an Axis power.

Great Britain

  • Hitler’s next target was the island of Great Britain. Starting in June 1940, German warplanes began bombing Britain. However, the British had a new invention called radar. Radar warned the British when German aircraft were nearing. British fighter airplanes shot down many attackers. This battle, called the Battle of Britain, was the world’s first major battle fought in the air.
  • The Germans soon decided not to invade Britain. Instead, they dropped more bombs on London and other cities until May 1941.

War with Japan Begins

  • Great Britain, France, and the Netherlands ruled many islands in the Pacific Ocean. They ruled much of Southeast Asia as well. With these countries now at war, Japan saw an opportunity to take away their colonies. The Japanese began by taking French Indochina (now Laos, Cambodia, and Vietnam) in 1940 and 1941.

Pearl Harbor

  • On the morning of December 7, 1941, Japanese warplanes attacked U.S. warships at the Pearl Harbor naval base in Hawaii. They sank or crippled eight big battleships, destroyed more than 180 aircraft, and killed more than 2,000 Americans.

Pearl Harbor attack

  • The Pearl Harbor attack brought the United States into the war. Within a few days, the United States was at war with Germany and Italy as well.

The Philippines

  • Japan also bombed the Philippine Islands, which were a U.S. possession. U.S. and Philippine forces fought until the Japanese defeated them. The Philippines surrendered in May 1942. Japan also conquered Singapore, the Netherlands Indies (now Indonesia), and Burma (now Myanmar).

Coral Sea and Midway

  • The battles of the Coral Sea and Midway stopped the Japanese push. In the Coral Sea, near Australia, the Allies stopped a Japanese attack on the island of New Guinea in May 1942. In June, near the tiny island of Midway in the North Pacific Ocean, U.S. airplanes destroyed many of Japan’s ships. However, Japan still controlled a vast area.

End of the War with Germany

North Africa and Italy

  • In November 1942 Allied forces landed in Morocco and Algeria in North Africa. They defeated German and Italian forces in May 1943.
  • The Allies followed up their North African successes by invading Italy. Soon afterward, Italians overthrew Mussolini. Italy surrendered in September 1943. However, German troops still held most of the country. The Allies took Rome, the capital, on June 4, 1944.

D-Day and Battle of the Bulge

D-Day Invasion
  • June 6, 1944, is called D-Day. On that day, 156,000 troops from the United States, Britain, and Canada attacked the beaches of Normandy in northern France. After fierce fighting, the Allied armies moved inland. They freed Paris on August 25.
  • The Allies then moved toward Germany. To stop this advance, the Germans made one last attack on the Allies in December 1944. The Germans lost this fight, called the Battle of the Bulge, by January. In March 1945 the Allies drove rapidly into western Germany.

Germany Surrenders

  • By February 1945 it was clear that Germany would lose the war. The Allied leaders—U.S. president Franklin D. Roosevelt, British prime minister Winston Churchill, and Soviet premier Joseph Stalin—met in Yalta (now in Ukraine). There they made plans for Europe after the war.
  • Meanwhile, Soviet troops pushed through Germany from the east. By April 25 the Soviets had surrounded Berlin, the German capital. Hitler killed himself on April 30. Germany surrendered at midnight on May 8, 1945.

End of the War with Japan

Americans Reaction to Japanese in the United States

Island Warfare

  • In the Pacific Ocean, U.S. troops captured island after island from the Japanese. In February 1943, after six months of jungle warfare, U.S. forces drove the Japanese from Guadalcanal, one of the Solomon Islands. The United States captured Saipan in the Mariana Islands in July 1944. From Saipan, U.S. airplanes began bombing Japan.
  • In October 1944 soldiers led by U.S. general Douglas MacArthur landed in the Philippines. The United States captured the Philippine capital of Manila in March 1945.
  • U.S. forces landed on Iwo Jima in February 1945 and on Okinawa in April 1945. Both these islands belonged to Japan. During the fight for Okinawa, Japanese pilots made kamikaze attacks—they crashed their airplanes into U.S. ships on purpose. Eventually, though, U.S. forces captured both islands.

Hiroshima and Nagasaki

  • By 1945 scientists in the United States had invented the atomic bomb, a new weapon of immense power. On August 6, 1945, a U.S. airplane dropped an atomic bomb on Hiroshima, Japan. More than 70,000 people died from the explosion and fires. On August 9 another U.S. plane dropped an atomic bomb on the city of Nagasaki. Japan surrendered on September 2, 1945. This ended the war.
Atomic Bomb
Albert Einstein- created the math that allowed for the Atomic Bomb
Atomic Bomb on Display
Effects of the Atomic Bomb on humans

Results of the War

  • After the war’s end, the Allies divided Germany among themselves. The Allies also punished Nazi leaders after putting them on trial in Nuremberg, Germany. They punished Japan’s wartime prime minister, Tojo Hideki, as well.
  • After the war the United States and the Soviet Union were the most powerful countries in the world. Despite having been Allies, the two countries soon began a long struggle called the Cold War.

American Involvement in WW2

Even though the fighting in World War II was all the way across the Atlantic and Pacific Oceans, the war changed the lives of everyone in America. The war effort in the United State was often called the home front.


  • Because of the war, many products were in short supply. Metal had to be used to make tanks and battle ships. Medicine was needed for the battlefields. Also, some products were hard to get as they came from countries that were at war. Rubber for tires was especially difficult to get because much of it was imported from Southeast Asia. By the end of the war, many products were rationed. Each family would get ration stamps allowing them to buy a certain amount of a type of product. Products rationed included tires, automobiles, sugar, gasoline, meat, butter, and coal.

Women go to work

Sugar rationing
  • When World War II began in 1939 there were around 190,000 men in the US Army. By the time the war ended in 1945, there were over 10 million. On top of this, factories in the US were at full capacity making arms, tanks, ships, and vehicles for the war. There was a shortage of workers.
  • To fill the gap and help build supplies for the war, many women went to work. They took on tough physical labor jobs that previously had been done mostly by men. Women who went to work in factories were nicknamed Rosie the Riveter. They played a major role in keeping the factories running smoothly and producing much needed planes, tanks, and other arms for the war.
Rosie the Rivetor

Japanese Americans

  • At the time of the war there were many citizens of the United States of Japanese descent. After Pearl Harbor, many people didn't trust them and were worried that they would help Japan to invade America. In 1942 President Roosevelt signed a bill that ordered Japanese Americans to go to internment camps.
  • These camps were almost like prisons. They were guarded by soldiers and surrounded by barbed wire. Around 120,000 Japanese Americans were forced into the internment camps. They had to leave their homes, shops, and jobs. Many lost their homes and most of their possessions. In 1988 President Ronald Reagan signed a bill that gave reparations of $20,000 to the survivors. In 1989 President George H.W. Bush gave a formal apology.

Entertainment and Propaganda

  • The US government knew that Americans must stay united in the war effort in order to win the war. They created all sorts of posters that showed patriotism and ways that people could help with the war effort from home. There were also lots of wartime movies showing how brave the soldiers were and how evil Hitler and the enemy was. All movie scripts had to be approved by the government.
  • Many celebrities fought in the war. Baseball players such as Joe DiMaggio and Ted Williams enlisted and fought. Also movie stars such as Jimmy Stewart and Clark Gable joined the army. At one point the commissioner of Major League Baseball wrote a letter to President Roosevelt asking if professional baseball should continue during the war. Roosevelt responded that they should keep playing baseball because it was good for the country's morale.


  • After World War I most Americans concluded that participating in international affairs had been a mistake. They sought peace through isolation and throughout the 1920s advocated a policy of disarmament and nonintervention.
  • As the European situation became more worse, the United States continued to hold to its isolationist policy. As Italy prepared to invade Ethiopia, Congress passed the Neutrality Act of 1935, embargoing shipment of arms to either aggressor or victim.
  • Lend-Lease Act, passed in March 1941 after vehement debate, committed the United States to supply the Allies on credit.
  • On December 8, 1941, Congress with only one dissenting vote declared war against Japan (Pearl Harbor). Three days later Germany and Italy declared war against the United States; and Congress, voting unanimously, did the same.

Neutrality Ended

  • Although in retrospect U.S. entry into World War II seems inevitable, in 1941 it was still the subject of great debate.
  • Isolationism was a great political force, and many influential individuals were determined that U.S. aid policy stop short of war. In fact, as late as August 12, 1941, the House of Representatives extended the Selective Training and Service Act of 1940 by a vote of only 203 to 202.
  • Believing that Japan intended to attack the East Indies, the United States stopped exporting oil to Japan at the end of the summer.
  • In effect an ultimatum, since Japan had limited oil stocks and no alternative source of supply, the oil embargo confirmed Japan’s decision to eliminate the U.S. Pacific Fleet and to conquer Southeast Asia, thereby becoming self-sufficient in crude oil and other vital resources.
  • In a bold surprise attack, Japanese aircraft destroyed or damaged 18 ships of war at Pearl Harbor, including the entire battleship force, and 347 planes. Total U.S. casualties amounted to 2,403 dead and 1,178 wounded.


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