During which period did Britain significantly influence the Iraqi government?

Britain significantly influenced the Iraqi government primarily during the period following the First World War until the revolution of 1958. After the Ottoman Empire's defeat in World War I, Britain took control of Iraq under a League of Nations mandate, and this period of influence is often referred to as the British Mandate for Mesopotamia (1920-1932). During this time, the British established a constitutional monarchy in Iraq, installing Faisal I of the Hashemite family as the king in 1921.

Although Iraq gained formal independence in 1932, British influence continued through treaties that allowed them to maintain military bases and influence over the country's foreign policy. This relationship remained particularly strong during World War II when Britain reasserted direct military control in 1941 to defend Iraq from Axis influence. British influence started to wane after the war, but it was only after the 1958 revolution, which overthrew the monarchy and established a republic, that British influence effectively ended.