On December 7, 1941, the Japanese military attacked the American Naval Base at Pearl Harbor, Hawaii. On December 8, the United States declared war on Japan and entered World War II. Japanese Americans were involved in WWII in two very different ways. At home, Japanese Americans faced extreme discrimination from the government and citizens. In combat abroad, Japanese Americans were American war heroes.

• Pearl Harbor and Japanese Internment
• Korematsu v. United States (1944)
• 442nd Regimental Combat Team

Pearl Harbor and Japanese Internment
The United States's entrance in the war fueled anti-Japanese sentiment, particularly along the Pacific coast. On February 19, 1942, President Franklin Delano Roosevelt signed Executive Order 9066, which called for the internment of thousands of Japanese Americans. By 1943, over 110,000 Japanese were interned in relocation centers in Arkansas, Arizona, California, Idaho, Utah, and Wyoming. Families lived in overcrowded barracks that often had no running water and little heat. The last camp did not close until March 1946; seven months after the war had ended.

The Civil Liberties Act of 1988 formally apologized for the internment of Japanese-American citizens during World War II and authorized a reparations fund for internment survivors.

Korematsu v. United States (1944)
During WWII, Fred Korematsu and two other men were arrested and convicted for violating their curfews and failing report to the relocation centers. The men challenged their conviction and their case made it to the U.S. Supreme Court. In 1944, the Supreme Court upheld their convictions and justified their internment as a necessity of national security.
In 1983, the San Francisco Federal District Court reversed Korematsu's conviction. In 1998, President Clinton awarded Korematsu the Presidential Medal of Freedom for challenging the Japanese internment.

442nd Regimental Combat Team
During World War II, the 442nd Regimental Combat Team was an all Nisei (1st generation Japanese-American) unit from Hawaii and the mainland United States. The unit achieved many great feats abroad despite the discrimination they faced at home. For example, in October 1944 the 100th/442nd RCT rescued the "Lost Battalion," an American unit that was stranded and surrounded by German soldiers. The 442nd Regimental Combat Team was the most decorated unit for its size and length of service, in the history of the U.S. Military. In total, approximately 14,000 men served, ultimately earning 9,486 Purple Hearts and 21 Medals of Honor.