The onset of the Great Depression forced Congress to make cuts in the Army's personnel and budget. Some 53 bases were closed, but MacArthur managed to prevent attempts to reduce the number of regular officers from 12,000 to 10,000. MacArthur's main programs included the development of new mobilization plans. He grouped the nine corps areas together under four armies, which were charged with responsibility for training and frontier defense. He also negotiated the MacArthur-Pratt agreement with the Chief of Naval Operations, Admiral William V. Pratt. This was the first of a series of inter-service agreements over the following decades that defined the responsibilities of the different services with respect to aviation. This agreement placed coastal air defense under the Army. In March 1935, MacArthur activated a centralized air command, General Headquarters Air Force, under Major General Frank M. Andrews.