During World War II, the United States Army Air Forces (USAAF) established numerous airfields in California for training pilots and aircrews of USAAF fighters and bombers. Most of these airfields were under the command of Fourth Air Force or the Army Air Forces Training Command (AAFTC). However, Air Technical Service Command (ATSC), Air Transport Command (ATC) and I Troop Carrier Command used a significant number of airfields in a support role. A significant number of them had operational squadrons for air defense of the Pacific coastline and anti-submarine patrols, and one was even handed over to Civil Air Patrol pilots for their use.