When the U.S. Immigration Station closed in 1940, the site was turned over to the U.S. Army and renamed the North Garrison of Fort McDowell. It opened a prisoner of war (POW) processing center on December 8, 1941, one day after Japan attacked Pearl Harbor.
The fort's primary role was to send replacement troops overseas. POWs from Germany, Italy, and Japan; U.S. civilians with Japanese ancestry; foreign nationals; and American citizens were processed at the site.
Internees arriving at Fort McDowell would be physically searched, and their personal effects (including money) would be confiscated. They would be given a serial number, fingerprinted, photographed, examined by a medical officer, and assigned a bed in the prisoner of war barracks. After several weeks, internees would be sent to other internment camps across the United States.
At the end of the war, the North Garrison’s role shifted to repatriating all Japanese POWs back to Japan.