World War II

The Allies — chiefly the United States, Britain, the Soviet Union, and China — fought the Axis powers of Germany, Italy, and Japan. Franklin D. Roosevelt, Winston Churchill, and Joseph Stalin, the “Big Three,” coordinated strategy at Tehran (1943) and Yalta (1945).

Millions of Americans served, including about 900,000 African Americans, mostly in segregated units; 33,000 Japanese Americans, many of whose families were incarcerated at home; and more than 350,000 women in the military’s women’s branches and nurse corps.

Japan seized Manchuria in 1931 and went to war with China in 1937; Germany invaded Poland in September 1939, beginning the war in Europe. Most Americans wanted to stay out, but Roosevelt steered aid to Britain and, through the Lend-Lease Act of March 1941, to the nations fighting Germany and Italy. In the Pacific, the United States cut off oil, steel, and other war materials to Japan to pressure it to withdraw from China. Japan’s leaders, facing shortages and unwilling to retreat, decided to strike.

Pearl Harbor and the Pacific defensive (1941–1942). Japan’s surprise attack on Pearl Harbor on December 7, 1941, killed some 2,400 Americans. Japan overran the Philippines, where thousands of captured American and Filipino soldiers died on the Bataan Death March. In mid-1942 American naval victories at the Coral Sea and Midway crippled Japan’s naval offensive.

Europe and the Atlantic (1942–1944). Allied convoys and code-breaking won the Battle of the Atlantic against German submarines. American troops landed in North Africa in November 1942, then fought up the Italian peninsula. American and British bombers struck German industry and cities. On D-Day, June 6, 1944, Allied forces landed in Normandy; Paris was liberated about two months later.

Island hopping (1943–1945). In the Pacific, U.S. forces seized island after island, bypassing the strongest Japanese garrisons. Fighting at Guadalcanal, Iwo Jima, and Okinawa was ferocious. In 1945 American bombers firebombed more than sixty Japanese cities; a single raid on Tokyo in March 1945 killed some 100,000 civilians.

Victory (1945). Soviet forces took Berlin in May 1945, days after Hitler’s suicide, and Germany surrendered. Roosevelt had died on April 12; his successor, Harry S. Truman, approved the use of atomic bombs on Hiroshima (August 6) and Nagasaki (August 9). Japan announced its surrender on August 15 and signed it on September 2, 1945.

• Pearl Harbor (December 1941): ended American isolationism overnight.
• Midway (June 1942): stopped Japan’s advance in the Pacific.
• The Battle of the Atlantic: kept supplies flowing from America to Britain and the Soviet Union.
• D-Day (June 1944): opened a second front in western Europe.
• The atomic bombings (August 1945): brought the Pacific war to a sudden end and began the nuclear age.

The Allies won. Germany and Japan were occupied, and their leaders were tried for war crimes. As the Allies advanced, they uncovered the full scale of the Holocaust: the Nazi regime had murdered six million Jews and millions of others. The United States helped found the United Nations, but the wartime alliance with the Soviet Union quickly gave way to the Cold War.

The war ended the Great Depression. Government spending in four years of war doubled all federal spending in the nation’s history up to that point, unemployment virtually disappeared, and the economy that emerged was larger than ever. Millions of women went to work in factories and offices, symbolized by “Rosie the Riveter,” though most left or lost those jobs when the men returned. The Bracero Program brought Mexican contract workers to American farms and railroads.

The war also exposed the nation’s contradictions. About 120,000 Japanese Americans were forcibly removed and incarcerated under Executive Order 9066. Black Americans, fighting in a segregated military, launched the “Double V” campaign for victory over fascism abroad and racism at home; NAACP membership grew tenfold, and about 1.5 million Black Southerners moved north and west in the 1940s. The G.I. Bill opened college and home ownership to millions of veterans.