An expanded Brigade group called Habforce had during the Anglo-Iraqi war advanced across the desert from Trans-Jordan to relieve the British garrison at RAF Habbaniya on the Euphrates River and had then assisted in the taking of Baghdad.
From 6 May 1941 the 4th Cavalry Brigade, together with a battalion of infantry from the Essex Regiment, a mechanised regiment from the Arab Legion and supporting artillery was organised as Habforce for operations in Iraq including the relief of the base at RAF Habbaniya and the occupation of Baghdad.
During the Anglo-Iraqi War, Brigadier Kingstone was under the command of Major General J. G. W. Clark and was part of his relieving Habforce which included the British 4th Cavalry Brigade, a battalion of The Essex Regiment, the Arab Legion Mechanised Regiment, a field artillery battery and a troop of anti-tank guns).