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World War II: 1939–1952


Big Three

United States, Britain, and the Soviet Union. These were the three most powerful of the Allied nations during the war.

Day of Infamy speech

President Roosevelt's call to Congress to declare war against Japan because of the empire's "infamous" attack on Pearl Harbor

Enola Gay

American B-29 bomber plane carrying an atomic bomb nicknamed Little Boy. It dropped the first atomic bomb on Hiroshima, Japan, on August 6, 1945.

Executive Order 9066

presidential order issued by President Roosevelt in 1942 that authorized the military to evacuate from the West Coast any people thought to be a security risk. Although the order did not single out any specific group of individuals, it was used to force Japanese Americans from their homes into detention camps.

Fat Man

second atomic bomb targeting Japan, dropped on the city of Nagasaki on August 8, 1945


Japanese city and target of the first atomic bomb, dropped by U.S. forces on August 6, 1945

Lend-Lease Act of 1940

law that gave the president the power to lend equipment and supplies to allies he considered vital

Little Boy

atomic bomb dropped from the Enola Gay on Hiroshima, Japan, on August 6, 1945

Manhattan Project

code name for a secret American program to develop and build an atomic bomb. This program was in response to concerns the Germans were developing atomic weapons for use against the Allies.


Japanese city and target of the second atomic bomb, dropped on August 8, 1945

Navajo code talkers

Native American servicemembers who transmitted top-secret military communications in their native language


position of not supporting either side in a conflict

Pearl Harbor

main base of the U.S. Pacific Fleet on the Hawaiian island of Oahu. Japan's attack on December 7, 1941, prompted the United States to enter World War II.

Potsdam Conference

meeting in late summer 1945 held in the Berlin suburb of Potsdam. The goal of the conference was to finalize plans for Germany's occupation and reconstruction.

Rosie the Riveter

character who became the face of the government's publicity campaign to draw more women into the workforce

Tuskegee Airmen

600 African Americans who trained as pilots at the Tuskegee airfield

V-E Day

Victory in Europe Day. Declared on May 8, 1945, it marked the end of the war in Europe.

V-J Day

Victory over Japan Day. Historic day celebrated on two different dates in the United States—August 14, 1945, when Japanese forces surrendered, and September 2, 1945, when Japan signed formal surrender documents.


members of the Women's Army Corps


members of Women Accepted for Volunteer Emergency Services—the U.S. Navy corps of female service personnel

Yalta Conference

meeting held in the Soviet Union for planning the final stages of the war, as well as the division and occupation of postwar Germany by the Allied forces