Authorized by the National Defense Act of 1920, which amended the National Defense Act of 1916, nine multi-state sized "corps areas" were established on 20 August 1920 by the U.S. Army Chief of Staff through War Department General Order Number 50. The corps areas were formed for administration, training, and tactical control of the army, replacing the six geographical (or territorial) military departments into which the continental United States had been divided since 1917 and with little variation since the Civil War. Three overseas commands: the Hawaiian Department, Panama Canal Department, and the Philippine Department continued to be identified as departments.