アングロ＝イラク戦争
Also, on 29 April, the British Ambassador, Sir Kinahan Cornwallis, advised that all British women and children should leave Baghdad; 230 civilians were escorted by road to Habbaniya and during the following days, were gradually airlifted to Shaibah. A further 350 civilians took refuge in the British Embassy and 150 British civilians in the American Legation.
By the end of the month, Colonel Roberts and 300 of the 1st KORR had been flown from RAF Shaibah to RAF Habbaniya to reinforce the latter base. Other than the 1st KORR, there were no trained British troops at Habbaniya bar the Number 1 Armoured Car Company RAF.
At 03:00 hours on 30 April, RAF Habbaniya was warned by the British Embassy that Iraqi forces had left their bases, at Baghdad, and were heading west. The Iraqi force was composed of between 6,000.–9,000. troops with up to 30 artillery pieces. Within a few hours of RAF Habbaniya being warned, Iraqi forces occupied the plateau to the south of the base. Prior to dawn, reconnaissance aircraft were launched from RAF Habbaniya and reported that at least two battalions, with artillery, had taken up position on the plateau.
By 1 May, the Iraqi forces surrounding Habbaniya had swelled to an infantry brigade, two mechanised battalions, a mechanised artillery brigade with 12 3.7-inch mountain howitzers, a field artillery brigade with 12 18-pounder field guns and four 4.5-inch howitzers, 12 Crossley six-wheeled armoured cars, a number of Fiat light tanks, a mechanised machine gun company, a mechanised signal company, and a mixed battery of anti-aircraft and anti-tank guns. This totalled 9,000 regular troops along with an undetermined number of tribal irregulars and about 50 field guns.
At 06:00 hours, an Iraqi envoy presented a message to the air officer commanding, Air Vice-Marshal Harry George Smart, stating that the plateau had been occupied for a training exercise. The envoy also informed Smart that all flying should cease immediately and demanded that no movements, either ground or air, take place from the base. Smart replied that any interference with the normal training carried out at the base would be treated as an act of war. Sir Kinahan Cornwallis, the British Ambassador located at the British Embassy in Baghdad and in contact with RAF Habbaniya via wireless, fully supported this action.
British reconnaissance aircraft, already in the air, continued to relay information to the base; they reported that the Iraqi positions on the plateau were being steadily reinforced, they also reported that Iraqi troops had occupied the town of Fallujah.
At 11:30 hours, the Iraqi envoy again made contact with Air Vice-Marshal Smart and accused the British of violating the Anglo-Iraqi treaty. Air Vice-Marshal Smart replied that this was a political matter and he would have to refer the accusation to Ambassador Cornwallis. Meanwhile, Iraqi forces had now occupied vital bridges over the Tigris and Euphrates rivers as well as reinforcing their garrison at Ramadi; thus effectively cutting off RAF Habbaniya except from the air.
During the morning, Smart and Roberts surveyed the situation, they determined that they were exposed to attack on two sides and dominated by Iraqi artillery; a single hit from an Iraqi gun might destroy the water tower or power station and, as a result, cripple resistance at Habbaniya in one blow – the base seemed at the mercy of the Iraqi rebels. The garrison did not have enough small arms and, apart from a few mortars, no artillery support.
Air Vice-Marshal Smart controlled a base with a population of around 9,000 civilians that was indefensible with the force of roughly 2,500 men currently available. The 2,500 men included air crew and Assyrian Levies, who were prized by the British for their loyalty, discipline and fighting qualities. There was also the possibility that the Iraqi rebels were waiting for dark before attacking. As a result, Air Vice-Marshal Smart decided to accept the tactical risks and stick to Middle East Command's policy of avoiding aggravation in Iraq by, for the moment, not launching a pre-emptive strike.
Further exchanges of messages took place between the British and Iraqi forces but none were able to defuse the situation. Air Vice-Marshal Smart again requested reinforcements and this time Air Officer Commanding Sir Arthur Longmore ordered 18  Vickers Wellington bombers to RAF Shaibah. The British Ambassador signalled the Foreign Office that he regarded the Iraqi actions as an act of war, which required an immediate air response. He also informed them that he intended to demand the withdrawal of the Iraqi forces and permission to launch air strikes to restore control, even if the Iraqi troops overlooking Habbaniya did withdraw it would only postpone aerial attacks.
Also on 1 May, Ambassador Cornwallis received a response giving him full authority to take any steps needed to ensure the withdrawal of the Iraqi armed forces. Churchill also sent a personal reply, stating: "If you have to strike, strike hard. Use all necessary force." In the event that contact broke down between the British Embassy in Baghdad and the air base in Habbaniya, Air Vice-Marshal Smart was given permission to act on his own authority.
Still in contact with the British Embassy and with the approval of Ambassador Cornwallis, Air Vice-Marshal Smart decided to launch air strikes against the plateau the following morning without issuing an ultimatum; as with foreknowledge the Iraqi force might start to shell the airbase and halt any attempt to launch aircraft.
Most combat operations of the Anglo-Iraqi War centred on the Habbaniya area. Starting early on 2 May, British airstrikes were launched against the Iraqis from RAF Habbaniya. While the largest number of British troops were ultimately assembled in the Basra area, an advance from Basra was not immediately practicable and did not get under way until after Rashid Ali's government was already collapsing. Initially, the Iraqi siege of RAF Habbaniya and the ability of the besieged British force there to withstand the siege was the primary focus of the conflict. Air Vice-Marshal Smart's decision to strike at the Iraqi positions with air power not only allowed his force to withstand the siege, but to neutralise much of Iraq's air power. While the relief force from Palestine arrived in Habbaniya after the siege was over, it did allow an immediate change over to the offensive.
Air Vice-Marshal Smart's tactics to defend Habbaniya was to mount continuous bombing and strafing attacks with as many aircraft as possible. At 05:00 on 2 May 33 aircraft from Habbaniya, out of the 56 operational aircraft based there, and eight Wellington bombers, from Shaibah, began their attack. A few of the Greek pilots being trained at Habbaniya also joined in the RAF attack. Within minutes the Iraqis on the escarpment replied by shelling the base, damaging some planes on the ground. The Royal Iraqi Air Force (RIrAF) also joined in the fray over Habbaniya. RAF attacks were also made against Iraqi air fields near Baghdad, which resulted in 22 aircraft being destroyed on the ground; further attacks were made against the railway and Iraqi positions near Shaibah, with the loss of two planes. Throughout the day, the pilots from Habbaniya flew 193 sorties and claimed direct hits on Iraqi transports, armoured cars and artillery pieces; however five aircraft had been destroyed and several others had been put out of service. On the base 13 people had lost their lives and a further 29 wounded, including nine civilians.
By the end of the day, the Iraqi force outside of Habbaniya had grown to roughly a brigade.
The British attack on 2 May took the Iraqis completely by surprise. While the Iraqis on the escarpment carried live ammunition, many Iraqi soldiers were under the impression that they were on a training exercise. Rashid Ali and the members of the Golden Square were shocked by the fact that the British defenders at RAF Habbaniya were prepared to fight rather than negotiate a peaceful surrender. To compound the surprise and shock, many members of the Muslim Iraqi army were preparing for morning prayers when the attack was launched. When the news reached the Grand Mufti in Baghdad, he immediately declared a jihad against the United Kingdom. In addition, the flow of Iraq Petroleum Company oil to Haifa was completely severed.
On 3 May, the British bombing of the Iraqis continued; troop and gun positions on the plateau were targeted as well as the supply line to Baghdad. The RIrAF base at Rashid was also attacked and an Iraqi Savoia SM 79 bomber was intercepted and shot down heading for Habbaniya. The following day further air attacks were carried out on RIrA troop positions and the RIrAF. A bombing raid was conducted by eight Wellington bombers on Rashid, which was briefly engaged by Iraqi fighters but no losses were suffered. Bristol Blenheims, escorted by Hurricanes, also conducted strafing attacks against airfields at Baghdad, Rashid and Mosul.
On 5 May, due to a car accident, Air Vice-Marshal Smart was evacuated to Basra and then onward to India. Colonel Roberts assumed de facto command of the land operations at RAF Habbaniya after the departure of Smart. Air Vice-Marshal John D'Albiac, from Greece, was to take command over aerial forces at Habbaniya and of all RAF forces in Iraq. Further aerial attacks were conducted against the plateau during the day and following nightfall Colonel Roberts ordered a sortie by the King's Own Royal Regiment (1st KORR) against the Iraqi positions on the plateau. The attack was supported by the Assyrian levies, some RAF armoured cars and two First World War-era 4.5-inch howitzers. The 4.5 in howitzers had been put in working order by some British gunners who had previously been decorating the entrance of the base's officers' mess.
Late on 6 May, the Iraqis besieging Habbaniya pulled out. By dawn on Wednesday 7 May, RAF armoured cars reconnoitred the top of the escarpment and reported it to be deserted. The Iraqi force had abandoned substantial quantities of arms and equipment; the British garrison gained six Czechoslovakian-built 3.7 inch howitzers along with 2,400 shells, one 18-pounder gun, one Italian tank, ten Crossley armoured cars, 79 trucks, three 20 mm anti-aircraft guns with 2,500 shells, 45 Bren light machine-guns, eleven Vickers machine guns, and 340 rifles with 500,000 rounds of ammunition.
The investment of Habbaniya, by Iraqi forces, had come to an end. The British garrison had suffered 13 men killed, 21 badly wounded, and four men were suffering battle fatigue. The garrison had inflicted between 500 and 1000 casualties on the besieging force, and numerous more men had been taken prisoner. On 6 May alone, 408 Iraqi troops were captured. The Chiefs-of-Staff now ordered that it was essential to continue to hit the Iraqi armed forces hard by every means available but avoiding direct attacks on the civilian population. The British objective was to safeguard British interests from Axis intervention in Iraq, to defeat the rebels and discredit Rashid's government.