During World War II, the Airport was leased to the U.S. Government on a "Dollar a Year Lease" for the purpose of constructing and operating an United States Army Air Forces Basic Training Air Field. Chico Army Airfield was under the command of the 10th Army Air Force Base Unit, AAF West Coast Training Center, Fourth Air Force. Chico Army Airfield was a major training site for thousands of pilots, both as a primary training base flying BT-13's, and for advanced gunnery and multi-engine training in P-38, P-39, P-63, B-17, B-29's.