During 1940/41 Iraq joined the Axis powers and the Battle of Habbaniya took place. During the Rashid Ali rebellion in 1941 the base was besieged by the Iraqi Army encamped on the overlooking plateau. The siege was lifted by the units based at Habbaniya, including pilots from the training school, a battalion of the King's Own Royal Regiment flown in at the last moment, No. 1 Armoured Car Company RAF, and the RAF's Iraq Levies. The subsequent arrival of a relief column ("Kingcol"), part of "Habforce" sent from Palestine, then a British mandate, combined with the Habbaniya units to force the rebel forces to retreat to Baghdad. The Levies then recruited an additional 11,000 men, mostly Assyrians, but also some Kurds and Yezidi.