On May 22, 1953, a U.S.-Ethiopian Mutual Defense Assistance Agreement was signed. A U.S. Military Assistance Advisory Group was dispatched to Ethiopia, and began its work by reorganising the army into three divisions. On 25 September 1953, Selassie created the Imperial Ministry of National Defense that unified the Army, Air Force, and Navy. By 1956, the First Division had its headquarters at Addis Ababa (First, Second, Third Brigades, 5,300 strong); the Second Division was headquartered at Asmara, with the Fifth, Sixth, Seventh, Eighth, and Twelfth Brigades (4,500 strong); and Third Division Harar (with the Fourth, Ninth, Tenth, and Eleventh Brigades, 6,890 strong) respectively. The three divisions had a total of 16,832 troops. In May 1959, the Emperor established the Imperial Territorial Army as a reserve force that provided military training to civil servants.