The 442nd Regimental Combat Team of the United States Army was a regimental size fighting unit composed almost entirely of American soldiers of Japanese descent who fought in World War II, despite the fact many of their families were subject to internment. The 442nd, beginning in 1944, fought primarily in Europe during World War II. The 442nd was a self-sufficient force, and fought with uncommon distinction in Italy, southern France, and Germany. The 442nd is considered to be the most decorated infantry regiment in the history of the United States Army. The 442nd was awarded eight Presidential Unit Citations and twenty-one of its members were awarded the Medal of Honor for World War II. The 442nd's high distinction in the war and its record-setting decoration count earned it the nickname "Purple Heart Battalion." The 442nd Regimental Combat Team motto was, "Go for Broke".
Most Japanese Americans who fought in World War II were Nisei, Japanese Americans born in the United States. Shortly after the Japanese attack on Pearl Harbor on 7 December 1941, Japanese American men were initially categorized as 4C (enemy alien) and therefore not subject to the draft. On 19 February 1942, President Franklin D. Roosevelt signed Executive Order 9066, authorizing military authorities “to prescribe military areas in such places and of such extent as he or the appropriate Military Commander may determine, from which any or all persons may be excluded, and with respect to which, the right of any person to enter, remain in, or leave shall be subject to whatever restrictions the Secretary of War or the appropriate Military Commander may impose in his discretion.” Although the order did not refer specifically to people of Japanese ancestry, it set the stage for the internment of people of Japanese descent. In March 1942, Lieutenant General John L. DeWitt, head of the Western Defense Command and Fourth Army, issued the first of 108 military proclamations that resulted in the forced relocation from their residences to guarded relocation camps of more than 110,000 people of Japanese ancestry on the West Coast.
In Hawai'i, martial law, complete with curfews and blackouts, was imposed. A large portion of the population was of Japanese descent (150,000 out of 400,000 people in 1937) and internment was deemed not practical, mostly for economic reasons. If the government had interned the Japanese Americans and immigrants in Hawai'i, the economy would not have survived. When the War Department called for the removal of all soldiers of Japanese ancestry from active service in early 1942, General Delos C. Emmons, commander of the U.S. Army in Hawaii, decided to discharge those in the Hawaii Territorial Guard, which was composed mainly of ROTC students from the University of Hawaii. But, he kept the more than 1,300 Japanese American soldiers of the 298th and 299th Infantry regiments of the Hawaii National Guard. The discharged members of the Hawaii Territorial Guard petitioned General Emmons to allow them to assist in the war effort. The petition was granted and they formed a group called the Varsity Victory Volunteers, which performed various military construction jobs. General Emmons, worried about the loyalty of Japanese American soldiers in the event of a Japanese invasion, recommended to the War Department that those in the 298th and 299th regiments be organized into a “Hawaiian Provisional Battalion” and sent to the mainland. The move was authorized, and on 5 June 1942, the Hawaiian Provisional Battalion set sail for training. They landed at Oakland, California on 10 June 1942 and two days later were sent to Camp McCoy, Wisconsin. On 15 June 1942, the battalion was designated the 100th Infantry Battalion (Separate)—the “One Puka Puka”.