By 1939 Iraq had been independent from Britain for seven years, and had built up a small army of five divisions (two of them based in Baghdad), a small river flotilla, and a small air force of 56 obsolete planes. As a prelude to independence, the Anglo-Iraqi Treaty of 1930 preserved for Britain important stakes in Iraq, namely commercial interests in the Mosul and Kirkuk oil fields and air bases near Baghdad and Basra. For the protection of these air bases, the British also maintained a reduced form of the native Iraq Levies. Due to the important strategic land and air link with India, Britain also had the right to move troops through Iraq. These restrictions on Iraqi independence fueled resentment and nationalist unrest, but the government of Nuri es-Sa'id remained pro-British.

      In September 1939 Sa'id wanted to declare war on Germany, but due to the pressure of nationalist factions was only able to sever diplomatic relations. In March 1940, he was replaced by Rashid Ali, but retained as foreign minister in the new government. Ali was the mouthpiece of the openly pro-Axis Golden Square, and he launched intrigues against Britain. Following British successes in North Africa, Ali resigned and his successor moved to crush the Golden Square. A military coup re-installed Ali as prime minister on 3 April 1941. Encouraged by hints of German assistance and swift German triumphs in Greece and Crete, Ali began to move against the British by abrogating the 1930 British treaty rights and beseiging the air base of Habbaniya. The Vichy French government in Syria also aided the Ali government and a conduit for German assistance.

      Although Gen. Wavell, the British commander in the Middle East, felt over-committed and short-changed of resources, and that Iraq was a minor irritant, PM Churchill insisted on overthrowing the Ali regime in order to preserve Britain's strategic interests in the region. An Indian division sailed for Basra, and the hybrid Habforce of a British brigade and the Arab Legion was assembled in Jordan.

     Although the British threw a relatively small force at the problem, the ill-equipped and trained Iraqi forces were no match. The Iraqis acted too soon, and their German aid was too little too late. The besieged air force in Habbaniya took the offensive and destroyed the Iraqi air force. Joining with the two relief columns coming from Jordan and Basra, they in turn besieged Baghdad which quickly capitulated. Nuri es-Said was eventually restored as prime minister, and a year later his government declared war on the Axis. No sooner was the Iraq operation over, than the country became the staging area for invasions of Syria and Iran to secure the greater region and its petroleum resources for the Allied war effort. Persia and Iraq Command was established in Baghdad to organise up to sixteen divisions for defence of the region against expected German invasion through the Caucasus. But the German advance was halted at Stalingrad, and by early 1943 British divisions were being moved to other theatres. Persia and Iraq Command dwindled to a strength needed only for internal security.

     While British intervention in Iraq had served the short-term war goals of the Allies, the long term effect was only to further aggravate nationalist sentiment. In 1958 a military coup deposed the monarchy and evicted the British from their bases. Although the British had completely withdrawn from the Middle East by 1970 and their influence in the region had been eclipsed by the Americans, the progressively tyrannical regime in Baghdad saw the British return two more times. In 1991 an Anglo-American-led coalition contained Iraqi expansionism, and in 2003 returned to finish the job of "regime change". The latter operation had forgotten the lessons of 1941.

• The Battle for Habbaniya and Falluja, by Gaby Kiwarkis.
• The Siege and Battle of Habbaniya in 1941 (RAF Habbaniya Association site)
• The Battle for Habbaniya - The forgotten war (RAF Official History)
• The Communications Flight RAF Station Habbaniya, by Michael A.R. Skeet

• Arab Legion Mechanised Brigade, WWII, by Steve Rothwell.
• Iraq Army April 15, 1941, by Ravi Rikhye (Orbat.com)
• Persia and Iraq Command

• General History
  • The Other "Gulf War"—The British Invasion of Iraq in 1941 by Douglas Porch (Center for Contemporary Conflict)
  • Anglo-Iraq War (1941), by Roger A. Lee (The History Guy)
  • Iraq in World War II (Library of Congress Country Study)
  • La Rivolta dell'Iraq, by Phantom (II Guerra Mondiale)
  • Despatch on Operations in Iraq, East Syria and Iran from 10th April, 1941 to 12th January 1942, by Sir Archibald Wavell (London Gazette 37685, 1946)
  • Operations in the Middle East [Feb. 1941-July 1941], by Gen. Sir Archibald Wavell (London Gazette 37638, 1946)
  • Operations in the Middle East [July 1941-Oct. 1941], by Gen. Sir Claude Auckinleck (London Gazette 37695, 1946)