Syrian-based Vichy air force units saw action against the British from April 1941, when a "coup d'état" in Iraq briefly installed the nationalist Rashid Ali Al-Gaylani as prime minister in order to secure the vital oil supplies at Kirkuk (under British control since 1934) in northeastern Iraq for the pro-Axis nationalists who wanted the British to be expelled from the country. However, the RAF base at Habbaniya withstood the nationalists, and in May the British, Indian and Commonwealth "Iraqforce" invaded Iraq "via" Basra. The ensuing Anglo-Iraqi War ended with Iraqforce defeating the nationalists at the end of May and restoring a pro-Allied government in Iraq.