History of Hawaii
Pearl Harbor was surprisingly attacked on December 7, 1941 by the Imperial Japanese Navy, killing 2,403 people and sinking the main American battleship fleet. Fortuitously, the four Pacific aircraft carriers were not in port and escaped damage. Hawaii was put under martial law until 1945. Unlike the West Coast of the United States in which 100,000 ethnic Japanese citizens were interned, the Japanese American population in Hawaii completely avoided such similar fate, though hundreds of pro-Japan leaders were arrested. Pearl Harbor was the U.S.' main forward base for the Pacific War. The Japanese tried to invade in summer 1942 but were defeated at the Battle of Midway. Hundreds of thousands of American soldiers, sailors, Marines, and airmen passed through on their way to the fighting.
Presidency of Franklin D. Roosevelt
The attack on Pearl Harbor raised concerns in the public regarding the possibility of sabotage by Japanese Americans. This suspicion was fed by long-standing racism against Japanese immigrants, as well as the findings of the Roberts Commission, which concluded that the attack on Pearl Harbor had been assisted by Japanese spies. The size of the Japanese population in Hawaii precluded mass internment in that territory, but there was strong popular support for the removal of Japanese from the West Coast. In February 1942, President Roosevelt signed Executive Order 9066, which provided for the relocation of hundreds of thousands of Japanese-American citizens and immigrants from the West Coast. They were forced to liquidate their properties and businesses and interned in hastily built camps in interior, harsh locations. Distracted by other issues, Roosevelt had delegated the decision for internment to Secretary of War Stimson, who in turn relied on the judgment of Assistant Secretary of War John J. McCloy. The Supreme Court upheld the constitutionality of the executive order in the 1944 case of "Korematsu v. United States". The internment order was rescinded shortly after the "Korematsu" decision, and Japanese-Americans were allowed to return to the West Coast. Many German and Italian citizens were also arrested or placed into internment camps.