The Anglo-Iraqi War was a British-led Allied military campaign during the Second World War against the Kingdom of Iraq, then ruled by Rashid Ali al-Gaylani who had seized power in the 1941 Iraqi coup d'état with assistance from Germany and Italy. The campaign resulted in the downfall of Gaylani's government, the re-occupation of Iraq by the British, and the return to power of the Regent of Iraq, Prince 'Abd al-Ilah, a British ally.
Mandatory Iraq had been governed by the British since 1921. Prior to Iraq's nominal independence in 1932, Britain concluded the Anglo-Iraqi Treaty of 1930, which was opposed by Iraqi nationalists, including Rashid Ali al-Gaylani. Although Iraq was considered a neutral power under Regent Abd al-Ilah, it had a pro-British government. In April 1941, Iraqi nationalists organized the Golden Square coup, with assistance from Nazi Germany and Fascist Italy. The coup ousted Abd al-Ilah and installed al-Gaylani as Prime Minister. He officially established cordial relations with the Axis powers, prompting the Allies to respond. For the Allies, Iraq represented an important land bridge between British forces in Egypt and India.
Following a series of skirmishes, Allied airstrikes were launched against Iraq on 2 May. The campaign resulted in the collapse of al-Gaylani's short-lived government, and re-installed Abd al-Ilah as the Regent. This increased the influence of the Allies in the Middle Eastern theatre.
The Kingdom of Iraq (also referred to as Mesopotamia) was governed by Great Britain under a League of Nations mandate, the British Mandate of Mesopotamia, until 1932, when Iraq became nominally independent. Before granting independence, Britain concluded the Anglo-Iraqi Treaty of 1930, which included permission to establish military bases for British use, and allowed unrestricted movement of British forces through the country upon request to the Iraqi government. The conditions of the treaty were imposed by the British to ensure control of Iraqi petroleum. Many Iraqis resented these conditions which left Iraq still under the control of the British Government.
After 1937, no British troops were left in Iraq and the government had become solely responsible for internal security. The Royal Air Force (RAF) had been allowed to retain two bases: RAF Shaibah, near Basra and RAF Habbaniya (Air Vice-Marshal Harry George Smart, also air officer commanding RAF Iraq Command), between Ramadi and Fallujah. The bases protected British petroleum interests and were a link in the air route between Egypt and India. At the beginning of the Second World War, RAF Habbaniya became a training base, protected by No. 1 Armoured Car Company RAF and locally raised mainly Assyrian troops, the RAF Iraq Levies, sometimes known as Assyrian levies.
In September 1939, the Iraqi Government broke off diplomatic relations with Nazi Germany. In March 1940, the nationalist and anti-British Rashid Ali replaced Nuri as-Said as Prime Minister of Iraq. Rashid Ali made covert contacts with German representatives in Ankara and Berlin, though he was not yet an openly pro-Axis supporter. In June 1940, when Fascist Italy joined the war on the side of Germany, the Iraqi government did not break off diplomatic relations. The Italian Legation in Baghdad became the chief centre for Axis propaganda and for fomenting anti-British feeling. The Italians were aided in their propaganda efforts by Amin al-Husseini, the Grand Mufti of Jerusalem, who had been installed by the British in 1921. The Grand Mufti had fled from the British Mandate of Palestine shortly before the war, and later received asylum in Baghdad. In January 1941, Rashid Ali resigned as prime minister and was replaced by Taha al-Hashimi amidst a political crisis and a possible civil war.
On 31 March, the Regent of Iraq, Prince 'Abd al-Ilah, learned of a plot to arrest him and fled Baghdad for RAF Habbaniya. From Habbaniya he was flown to Basra and given refuge on the gunboat HMS Cockchafer. On 1 April, Rashid Ali and the Golden Square (four senior military commanders) seized power in a coup d'état. Rashid Ali proclaimed himself "Chief of the National Defence Government". The Golden Square deposed Prime Minister Taha al-Hashimi and Rashid Ali again became Prime Minister of Iraq. Ali did not overthrow the monarchy and named a new Regent to King Faisal II, Sharaf bin Rajeh. Faisal and his family took refuge in the home of Mulla Effendi. The Golden Square also arrested pro-British citizens and politicians, but many managed to escape through Transjordan.
The Golden Square intended to refuse further concessions to Britain, retain diplomatic links with Fascist Italy, and exile prominent pro-British politicians. They thought Britain was weak and would negotiate with them. On 17 April, Ali asked Germany for military assistance in the event of war with Britain. Ali also tried to restrict British rights under Article 5 of the 1930 treaty when he insisted that newly arrived British troops be quickly transported through Iraq and to Palestine.
Before the war, the United Kingdom provided support to the Royal Iraqi Army, to the Royal Iraqi Navy, and to the Royal Iraqi Air Force through a small military mission based in Baghdad, commanded from 1938 by Major-General G. G. Waterhouse. The Iraqi Army was composed of approximately 60,000 men, most in four infantry divisions and one mechanised brigade. The 1st and 3rd Divisions were stationed near Baghdad. Also based within Baghdad was the Independent Mechanised Brigade, composed of a light-tank company made up of L3/35 tankettes, an armoured-car company composed of Crossley armoured cars, two battalions of motorised infantry, machine-gunners and an artillery brigade. Unlike the contemporary use of the term "mechanised", it meant "motorised" in 1941 (moving in lorries, fighting on foot). The Iraqi 2nd Division was stationed in Kirkuk and the 4th Division in Al Diwaniyah, on the main rail line from Baghdad to Basra. The Iraqis fielded police units and about 500 irregulars under Arab guerrilla leader Fawzi al-Qawuqji, a ruthless fighter who did not hesitate to murder or mutilate prisoners. For the most part, Fawzi operated in the area between Rutbah and Ramadi, before being chased back into Syria.
The air force had 116 aircraft in seven squadrons, of which 50 to 60 were serviceable, and a training school. Most Iraqi fighter and bomber aircraft were at "Rashid Airfield" in Baghdad (formerly RAF Hinaidi) or in Mosul. Four squadrons and the Flying Training School were based in Baghdad. Two squadrons with close co-operation and general-purpose aircraft were based in Mosul. The Iraqis flew an assortment of aircraft types including Gloster Gladiator biplane fighters, Breda 65 fighter bombers, Savoia SM 79 medium bombers, Northrop/Douglas 8A fighter bombers, Hawker Hart (Hawker Nisr) biplane close co-operation aircraft, Vickers Vincent biplane light bombers, de Havilland Dragon biplane general purpose aircraft, de Havilland Dragonfly biplane general purpose aircraft and Tiger Moth biplane trainers. The air force had another nine aircraft not allocated to squadrons and 19 aircraft in reserve.
The Royal Iraqi Navy had four 100 long tons (100 t) Thornycroft gunboats, a pilot vessel and a minesweeper. All were armed and were based in the Shatt al-Arab waterways.
On 1 April 1941, the British forces in Iraq were small. Air Vice Marshal Harry Smart commanded British Forces in Iraq, a multi-service headquarters. Ground forces included Number 1 Armoured Car Company RAF and six companies of Assyrian Levies, composed of indigenous Eastern Aramaic speaking Christian Assyrians about 2,000 officers and other ranks strong, under the command of about twenty British officers. The armoured-car company had 18 old Rolls-Royce armoured cars, built for the RAF in 1921 on converted chassis of World War I design. The armoured car company had two large tanks (HMT 'Walrus' & 'Seal', based on Vickers Medium Dragon Mk 1 artillery tractors with Rolls-Royce turrets) and a Carden-Lloyd Mk VI tankette.