The United States Army Air Corps began negotiating for the use of Drew Field in 1939 during the buildup of military forces prior to World War II. In 1940, the City of Tampa leased Drew Field to the U.S. Government for 25 years, or until the end of the "national emergency." During the war, the United States Army Air Forces expanded and modernized the airport. The airfield was used by the Third Air Force and renamed it Drew Army Airfield. The Third Air Force used it as a training center by 120,000 combat air crews, primarily in bomber aircraft for the European and Pacific theaters, and also flew locally based antisubmarine patrols from the airfield until that mission was fully taken over by Naval Aviation assets of the U.S. Navy and U.S. Coast Guard. There was one mishap in 1943 that killed five fliers. Despite this, Drew Field set a safety record for the Third Air Force in 1945 after 100,000 flying hours had been completed over a period of 10 months without a fatal incident. The aircraft operated included the Boeing B-17 Flying Fortress, Douglas C-47 Skytrain, North American AT-6, North American B-25 Mitchell, and others.