During the late depression years (1938–July 1940), a new two-story passenger terminal building was constructed by the Works Progress Administration. On March 17, 1941 the airport was renamed General Mitchell Field after Milwaukee native and air power advocate Brigadier General William "Billy" Mitchell. On January 4, 1945, Mitchell Field was leased to the War Department for use as a World War II prisoner-of-war camp. Over 3,000 prisoners and 250 enlisted men stayed at the work camp. Escaped German prisoners were often surprised to find a large German American population just beyond the fence.