Sandia National Laboratories' roots go back to World War II and the Manhattan Project. Prior to the United States formally entering the war, the U.S. Army leased land near an Albuquerque, New Mexico airport known as Oxnard Field, to service transient Army and U.S. Navy aircraft. In January 1941 construction began on the Albuquerque Army Air Base, leading to establishment of the "Bombardier School-Army Advanced Flying School" near the end of the year. Soon thereafter it was renamed Kirtland Field, after early Army military pilot Colonel Roy C. Kirtland, and in mid-1942 the Army acquired Oxnard Field. During the war years facilities were expanded further and Kirtland Field served as a major Army Air Forces training installation.