Following the onset of World War II, the Army Air Corps launched an ambitious pilot training program that at its peak trained more than 100,000 pilots per year and led to the construction or improvement of more than 450 air fields across the U.S. North Alabama was chosen as a favorable region for a large training base because of its year-round flying climate and low airway congestion, and of three surveyed locations, the Courtland area was judged the best overall choice. In April 1942, a board headed by Colonel Aubrey Hornsby and Lieutenant Colonel Joseph Duckworth officially selected the site. Within eight months, runways, roads, and most buildings were constructed on 2200 acres acquired from the Bynum and Shackelford estates, and four smaller nearby auxiliary air fields were added for emergencies and training flexibility. The field was activated on 14 Dec 1942 under the command of the Southeast Air Corps Training Center, and the first cadet class arrived on 26 Jan 1943. Cadet pilots attended four schools—Preflight, Primary, Basic, and Advanced—and the field began service as a Basic Flight School, supplemented by Signal Corps training. Its program combined ground school classrooms with flight instruction, and cadet performance there determined whether they moved on to advanced fighter or bomber training or transferred to other schools for subjects such as navigation and aerial photography. Four interlocking 5000-foot runways made the field well suited for day and night training seven days per week in varied wind conditions, and it could host up to 700 cadets and 240 aircraft. The main Basic Flight School aircraft was the single-engine BT-13A Valiant. As Air Corps training needs changed, the Basic Flight School was replaced in September 1944 by a Four-Engine Specialized School, bringing personnel and B-24 Liberator bombers from Chanute Field, Illinois, while twin-engine trainers such as the Beechcraft AT-10 and Cessna UC-78 also served there.