In 1943, some branches of the military, including the Army, were opened to persons of Japanese ancestry. Counting draftees, volunteers, and pre-Pearl Harbor enlistees, more than 33,000 Japanese Americans served in World War II. Most served in segregated units with the 100th Battalion, a Hawaiian National Guard unit, and the 442nd Regimental Combat Team, a unit of mainland Nisei that combined with the 100th for service in Europe.

For its size and length of service, the 100th/442nd was the most decorated U.S. military unit in U.S. history. About 6,000 Nisei served in the Pacific theater with the Military Intelligence Service (MIS), using Japanese language skills to aid the American war effort. According to General MacArthur’s Intelligence Chief, the MIS was responsible for having “saved countless lives and shortened the war by two years.”

One effort, the quayule project, channeled the unique scientific and research talents of Manzanar residents in support of the war effort. When America’s rubber supply was cut off by Japanese incursions into Southeast Asia, government agencies sought alternative sources of rubber. During the spring of 1942, experiments in guayule rubber culture were undertaken at Manzanar. Dr. Robert Emerson, a Cal Tech professor and Quaker, assembled a group of internee scientists, horticulturists and laborers to develop rubber from guayule. Propagation beds, field plots, a chemical and a cytogenetics laboratory were built in camp. They successfully extracted natural rubber contained in the woody parts of this desert plant. Camp administrators and internees promoted the project both as a chance to allow internees to use their agricultural and scientific expertise and to contribute to the war effort.