In May 1964 troops began to withdraw, beginning with the Irish unit in Kolwezi on 11 May, and ending with units in Leopoldville in June. The United Nations also maintained a large civilian staff of 2000 experts in the country throughout 1963 and 1964. The final group of peacekeepers, 85 men of the First Nigerian Battalion and 58 men of the 57th Canadian Signals, departed Ndjili Airport in Leopoldville on 30 June. The last soldier to leave was UN Force Commander Major General Johnson Aguiyi-Ironsi.