'Countenance' was the Allied invasion and occupation of Iran to secure the Iranian oilfields and to assure the lines of communications by which Allied matériel could be delivered to the Soviet forces fighting the Axis forces on the Eastern Front (25 August/17 September 1941).

Though Iran was officially neutral, the Allies claimed that its monarch, Reza Shah, was predisposed toward the Axis powers, and the shah was therefore deposed during the subsequent occupation and replaced with his young son Mohammad Reza Pahlavi.

In 1925 years of civil war, internal and external turmoil, and foreign intervention had come to an end when Persia (Iran from 1935) was united under the rule of Reza Khan, who crowned himself to become Reza Shah in the same year. The new ruler embarked on a major programme of economic, cultural and military modernisation which started to turn Iran, which had been a backward, divided and isolated country under the rule of the Qajar dynasty, into a modern industrial state. Reza Shah’s improvement programme also included the construction of an economic and logistical infrastructure, the expansion of cities and transportation networks, and the establishment of schools. Reza Shah also attempted to turn Iran into neutral state, but to facilitate the financing and technical support of his modernisation projects had to call on the aid of the western nations.

For many decades, Iran and Germany had created and developed ties, in part to counter the imperial ambitions of the UK and Russia in its earlier tsarist and Soviet forms, and trade with Germany was attractive to Iran as the Germans had no history of imperialism in the region. The rise to power of the Nazi part in Germany did not have a major effect on this Iranian/German trade. While Nazi propaganda sometimes tried to play up the similarities between the two Aryan nations, in reality Iran had little affection for Nazi policies, including anti-Semitism.

Even so, British propaganda began to suggest that Iran did indeed support the Nazi concept and was therefore pro-German.

Although Reza Shah declared Iran’s neutrality at an early stage of World War II, Iran steadily assumed greater strategic importance in the eyes of the British, whose government feared that the Abadan Oil Refinery, owned by the UK-owned Anglo-Iranian Oil Company, might fall into German hands: this operation;s refinery produced eight million tons of oil in 1940, and was thus of critical significance in the Allied war effort. Tensions with Iran had been already strained since 1931, when Reza Shah had cancelled the D’Arcy Concession, which gave the Anglo-Iranian Oil Company the exclusive right to sell Iranian oil, for which Iran received a maximum of only 16% of the profits.

After Germany’s 'Barbarossa' invasion of the USSR in June 1941, the UK and USSR became formal allies, providing further impetus for an Allied intervention in Iran as the so-called 'Persian Corridor' formed by the Trans-Iranian Railway was one of the surest ways for the Allies to get desperately needed Lend-Lease supplies to the Soviets after these had reached Iran by sea from the USA. Recognising the vital importance of this railway, British and Soviet planners inevitably began to consider ways in which they could secure it. As increasing U-boat attacks and poor ice conditions made convoys to Murmansk and Arkhangyel’sk in the northern part of the USSR extremely dangerous, the railway acquired still greater desirability. The Soviets also desired to annex Iranian Azerbaijan into the USSR, and possibly turn Iran into a communist state. The two Allied nations applied increasing pressure on Iran and the shah, but this led only to increased tension and in Tehran anti-British rallies which British propaganda labelled as 'pro-German'.

Allied demands that all Germans resident in Iran should be expelled were refused by the shah, but under Allied pressure Iran did begin to reduce the volume and value of its trade with Germany. Reza Shah continued his efforts to maintain Iran’s neutral stance and placate both the Allied and the Axis powers, but this became increasingly problematical in the face of British and Soviet demands. There were already sizeable British forces in the region as a result of the Anglo-Iraqi War earlier in 1941, and thus there were British troops on Iran’s western border before 'Countenance'. This was the overall designation of the undertaking, whose British-led sub-components included 'Bishop' for the capture of the port and shipping at Bandar Shahpur, 'Marmalade' for the destruction of Iranian naval forces at Khorramshahr at the junction of the Shatt al-Arab waterway and the Karun river, 'Crackler' for the capture of the island of Abadan and its oil refinery and facilities, 'Demon' for the landing of troops at Abadan, 'Mop-up' for the naval and army clearance of the Iranian forces from the Khazalabad area between Khorramshahr and Abadan. 'Rapier' was unused, and would have been the designation for the capture of Abadan and Khorramshahr.

The Iranians claimed that the invasion was an undeclared surprise attack, through it could hardly have been a surprise after the clearly visible build-up of British and Soviet forces across Iran’s western and north-western frontiers, and not wholly undeclared as diplomatic notes had been delivered to the Iranian government on 19 July and 17 August informing it that unless Axis nationals were expelled force would be used against Iran. The second of the notes was seen by prime minister Ali Mansur as nothing but a disguised ultimatum. The British and Soviet ambassadors delivered final diplomatic notes, declaring that the invasion was starting, during the night of the invasion. The British believed that the invasion would not be a surprise, as evidenced by the fact that the Iranians had clearly expected a British advance into Khuzestan and sent reinforcements, including light and medium tanks, to Ahwaz. Even so, the invasion secured total tactical surprise.

Immediately after the start of the invasion, Iran summoned Sir Reader Bullard and Andrei Andreyevich Smirnov, the British and Soviet ambassadors, of whom the shah demanded to know why they were invading his country and why had not they declared war. Both answered that it was because of the presence of 'German residents' in Iran. When the shah asked if the Allies would stop their attack if he expelled the Germans, the ambassadors did not answer.

British and Australian naval forces attacked from the Persian Gulf, British land and air forces from Iraq, and Soviet land, naval and air forces from the north. The main strength of the Soviet advance was provided by the 44^th, 47^th and 53^rd Armies of General Leytenant Dmitri T. Kozlov’s Trans-Caucasus Front, which had significant air support and also a large armoured element of more than 1,000 armoured fighting vehicles of which the T-26 tank was the most numerous.

Six days after the invasion and the ensuing Allied occupation of southern Iran, the British divisions of Lieutenant General E. P. Quinan’s Iraq Command (otherwise Iraqforce) was renamed as the Persia and Iraq Force (otherwise Paiforce). This comprised Major General C. O. Harvey’s Indian 8^th Division, Major General W. J. Slim’s Indian 10^th Division, Brigadier J. A. Aizlewood’s Indian 2^nd Armoured Brigade, Brigadier J. G. E. Tiark’s British 4^th Cavalry Brigade (later renamed 9^th Armoured Brigade) and Brigadier C. J. Weld’s Indian 21^st Brigade.

In sum, the Allies had 200,000 troops as well as modern artillery, armour and aircraft.

In response to the invasion, the Iranian army mobilised nine divisions, some of them motorised and two with modest numbers of tanks. The Iranian armed forces had a regular establishment of between 126,000 and 200,000 men. While Iran had taken numerous steps in the preceding decade to strengthen and standardise its army into a modern force, it lacked the training, armour and air power to fight a multi-front war. Part of this incapacity was the result of the fact that Reza Shah’s modernisation effort had been focussed on the creation of an army optimised for the suppression on internal dissent rather than the defeat of an external threat.

So far as matériel was concerned, Iran was self-sufficient in the manufacture of small arms. Iran had bought 100 Renault FT-6 light tanks from France and CKD/Praga THN-P light tanks from Czechoslovakia, as well as La France TK-6 armoured cars, to equip its 1^st and 2^nd Divisions, but the completion of further orders had been delayed by the outbreak of World War II. The Iranian air force had between 150 and 200 Hawker Audax army co-operation, Hawker Hind light bomber and Hawker Fury fighters. These had been good types when designed and built, but by World War II standards all were obsolete or at best obsolescent.

Before the start of 'Countenance' (including the 'Bishop', 'Crackler', 'Demon', 'Dover', 'Marmalade', 'Mop Up' and 'Rapier' sub-operations), British aircraft dropped leaflets on Iranian troops, asking them to not fight and telling them to understand that their country was merely being 'liberated' from the threat of Nazi destruction.

'Countenance' began early in the morning of 25 August as British warplanes entered Iranian airspace and proceeded to bomb targets in Tehran, Qazvin and a number of other towns, and also dropped leaflets urging the Iranians to surrender. The Soviets bombed targets in cities such as Tabriz, Ardabil and Rasht. Civilian and residential areas were hit, and several hundred people were killed and wounded. Reza Shah refused the urgings of his senior military commanders to authorise the destruction of Iran’s road and rail networks, largely because he was unwilling to see the sacrifice of the infrastructure which he had painstakingly built during his reign. This contributed to the speedy Allied victory.

Without any military allies to come to its assistance, Iran could offer a resistance which was rapidly overwhelmed and neutralised by British and Soviet infantry and armour. The British and Soviet forces met at Sanandaj (called Senna by the British) about 100 miles (160 km) to the west of Hamadan) and Qazvin (called Kazvin by the British) about 100 miles (160 km) to the west of Tehran and 200 miles (320 km) to the north-east of Hamadan on 30 and 31 August respectively. Faced with large and inescapable defeat, the shah ordered his military to surrender on 29 August, four days after the start of 'Countenance'.

In the south-western province of Khuzestan, bordering south-eastern Iraq, the British half of the campaign began on 25 August with naval attacks and landings in Abadan, Khorramshahr and Bandar Shapur. Under British command, the ships involved were the armed merchant cruiser Kanimbla, sloops Falmouth, Shoreham and Australian Yarra, river gunboat Cockchafer, corvette Snapdragon and some small auxiliary vessels. At Abadan Shoreham sank the Iranian sloop Palang, and the other Iranian vessels in the harbour were either destroyed or captured. In the mouth of the Karun river Yarra sank the gunboats Karcass and Chahbaaz, and in Khorramshahr Babr, sister-ship of the Italian-built Palang. The commander of the Iranian navy, Rear Admiral Gholamali Bayandor, was killed in the fighting at Khorramshahr. In Bandar Shapur the British-led naval forces captured several German freighters in the form of the 7,862-ton Hohenfels, 7,575-ton Marienfels, 6,288-ton Sturmfels and 6,224-ton Wildenfels, and Italian vessels in the form of the 4,769-ton tanker Bronte, 3,065-ton freighter Barbara, 5,225-ton freighter Cabot and, on 27 August at Bandar Abbas, in the 4,901-ton freighter Hilda. Her crew set fire to the 7,861-ton German freighter Weissenfels, which was destroyed.

There had not been time for the Iranians to prepare any realistic defence, and British and Indian troops occupied the oil installations at Abadan and Bandar Shapur before any attempt could be made to destroy them. The petroleum installations at Abadan were of vital importance to the British war effort, and the British commanders were also very concerned to ensure that the employees of the Anglo-Iranian Oil Company were safeguarded from possible reprisals. Khuzestan was defended by 27,000 men of the Iranian 1^st Division, 2^nd Division, 6^th Division and 16^th Division, consisting of both unmotorised and motorised infantry, and all of Iran’s armoured strength was deployed in Khuzestan as part of the 1^st Division and 2^nd Division. A British naval and army force landed at Abadan, securing the city and the refinery. The Iranians managed to put up a limited resistance, but the refinery and the city were captured after hand-to-hand combat, which resulted in the deaths of several British and Indian soldiers.

The Iranians were taken completely by surprise, and thus there was virtually no resistance, in other areas of Khuzestan. Bandar Shahpur was captured by two battalions of the Indian 8^th Division’s Indian 24^th Brigade, under the command of Brigadier R. E. Le Fleming, which made an amphibious descent from the Australian armed merchant cruiser Kanimbla to secure the port and petroleum terminal. British aircraft attacked air bases and communications, and rapidly gained air superiority. They destroyed numerous Iranian aircraft on the ground, and protected the British and Indian ground forces from Iranian counterattacks.

The Indian 8^th Division (Brigadier R. G. Lockner’s Indian 18^th Brigade and Brigadier R. G. Mountain’s Indian 25^th Brigade under command from the Indian 10^th Division) advanced from Basra across the Shatt al-Arab waterway toward Qasr Sheikh, which it took on 25 August, and captured Khorramshahr, Abadan’s neighbour, on the same day. The Karun river was not wholly secured, as there remained a number of Iranian snipers, and this slowed the British advance for a short time. The Britain also landed troops at Bandar Abbas, and secured the full length of the Shatt al-Arab.

By 26 August there was no organised Iranian resistance in the area. Overwhelmed by superior firepower and better tactics, the Iranian defence had crumbled, those who had not been killed either scattering or, in the case of more than 350 men, being taken prisoner.

The British hoped to capture Ahvaz and then to drive northward into the Zagros mountain passes to reach Qazvin, where they would link with British troops in central Iran, and Soviet troops advancing from the north. By a time early in the morning of 27 August, the British forces had reached Ahvaz. However, Iranian troops under the command of Major General Mohammad Shahbakhti had prepared a strong defence with infantry entrenched round the city, with artillery support and tanks. Although the Iranians had taken heavy losses and their morale was decreasing, they were prepared to stand and fight. The Indian advance came to a halt in the face of a crossing of the Karun river against a prepared defence, and a British attack on the defences was repelled by Iranian tanks and infantry. Whether the Iranians could have sustained their defence is moot, but on 29 August, after some more sporadic fighting, word reached the Iranian commanders at Ahvaz that the Iranian government had accepted a ceasefire and that no further resistance was to be offered. The British and Iranians agreed as part of the ceasefire that the Iranians would not lay down their arms and would remain at their posts, but would be joined by the British troops, who would parade through the city. In exchange, the Iranians would evacuate the city’s British residents to the protection of the British troops.

Farther to the the Indian 10^th Division attacked into central Iran. Slim was absent in India at the time, and had to direct operations remotely by radio. The Indian infantry and armour massed at the Iraqi border town of Khanaqin, some 100 miles 160 km) to the north-east of Baghdad and 300 miles (480 km) from Basra. Unlike the flat land of Khuzestan, the terrain over which the Indian troops were attacking in Kermanshah province was mountainous, with narrow roads and steep mountain passes.

The Indians crossed the border at the town of Qasr-e Shirin and moved into the Naft Shahr oilfield with little opposition. It was the British objective to complete the planned operation with the least possible Iranian casualties, but here the Indians faced opposition from 2,000 Iranian troops as they tried to capture the town of Gilan-e-Gharb about 20 miles (32 km) inside Iran. The Iranians hoped that a successful defence woulds prevent the Indians from moving through the Pai Tak pass.

The RAF provided close air support for the Indian troops, and its aircraft were involved in several dogfights with Iranian aircraft. The British suffered no air losses, and shot down six Iranian fighters and damaged several other aircraft. With complete air superiority, the British bombed targets in several of the area’s towns and dropped leaflets urging the Iranians to surrender.

The Indian troops captured Gilan-e-Gharb and then moved forward to attack the Iranian forces holding the town of Sarpol-e-Zahab. The combination of overwhelming British firepower and decreasing Iranian morale was decisive, and the Iranian defence quickly crumbled as the Indian troops surged forward to take Sarpol-e-Zahab and the remaining defenders scattered. The Pai Tak pass, and the road to Kermanshah and eventually Tehran, was therefore opened as the Indian columns secured the pass and the area round it.

The Indian forces next moved along the Kermanshah highway toward Shahabad (now Eslamabad-e Gharb). There was little Iranian resistance other than the felling of some trees and the demolition of a section of the road, which delaying the Indians for only a few hours.

The main Iranian forces in the region comprised the 5^th Division and 12^th Division, totalling about 30,000 men and supporting artillery, at Kermanshah and Sanandaj. These were orthodox infantry as the motorised, mechanised and armoured units had been stretched thin fighting on other fronts, and their chances of mounting a sustained defence were low. The Indians had reached the outskirts of Shahabad by a time early in the morning of 28 August after suffering several individually short delays. At the village of Zibri the Indians encountered an Iranian garrison willing to fight and suffered a number of casualties. Again, however, poor Iranian leadership and overwhelming Indian firepower combined to bring about an early decision in favour of the Indians, who then took Shahabad during the morning of the same day.

By 29 August, the Indians had reached Kerend, and were within 2 miles (3.2 km) of Kermanshah and preparing their attack on the city. At this point, the Iranian commanders received news of their government’s decision to agree to a ceasefire, and were ordered to stand down. They declared Kermanshah an open city, and the Indians entered it on 1 September. They also entered Sanandaj peacefully and eventually Qazvin, which had already been captured by the Soviets.

The Soviet forces also attacked on 25 August, starting with preliminary air attacks on Iranian air bases. The Soviet offensive involved three armoured spearheads, totalling more than 1,000 tanks and large numbers of motorised infantry. The first force, comprising General Major Vasili V. Novikov’s 47^th Army crossed the border and advanced from Soviet Azerbaijan into Iranian Azerbaijan in the direction of Tabriz and Lake Urmia. The 47^th Army captured Jolfa, and an Iranian reconnaissance aeroplane discovered the forces to the south of Jolfa moving toward Marand. It was feasible for Major General Matboodi’s Iranian 3^rd Division to move motorised infantry toward Shibli to check the breakthrough, but Matboodi was taken totally by surprise and failed to implement an effective counterattack. Matboodi also failed to destroy major roads and bridges, and this made it possible for the Soviets to move through the region with some speed. Iranian bombers tried to attack the Soviet positions around Jolfa, but were intercepted and mauled.

Meanwhile, General Major Sergei G. Trofimenko’s 53^rd Army crossed the border and moved toward Ardabil in an area held by Brigadier General Qaderi’s Iranian 15^th Division. Two Iranian regiments began to move toward Nir to tackle the 53^rd Army’s spearheads, but despite the number and quality of his well-motivated troops, Qaderi abandoned his men and fled in a car, further compounding his desertion by ordering that the supply trucks delivering food, weapons and artillery to be stripped of their loads to make way for his personal belongings. The Soviets bypassed Nir and moved south. Ardabil was bombed by Soviet aircraft, which inflicted minor damage on the town’s military barracks. Cut off and bypassed, both the 15^th Division in Ardabil and the 3^rd Division in Tabriz began collapse. Some of the regular troops tried to maintain order, and even began to move toward the Soviet forces without many of their commanders. Lacking food, supplies and ammunition, however, the troops were forced to abandon much of their heavy equipment. Pockets of resistance remained, and there was some desperate fighting before these pockets were overrun by the Soviet forces, which by 26 August had occupied the whole of Iranian Azerbaijan including Tabriz and Ardabil.

On 25 August, the Soviet attack on Gilan was launched by Kontr Admiral Fedor S. Sedelnikov’s Caspian Sea Flotilla, which comprised more than a dozen destroyers, patrol boats, anti-aircraft barges and landing craft. Facing them were three Iranian gunboats. Meanwhile, General Major Aleksandr A. Khadeyev’s 44^th Army crossed the border and moved into this Iranian province. it advanced along the Astara highway and the main coastal highway. The Soviets knew that there were significant Iranian forces in the area, and had planned that naval landing forces would secure the main Iranian ports along the southern coast of the Caspian Sea, and then be joined by the land forces. The flotilla landed troops and rapidly captured the border city of Astara, and then moved toward its next objective. The main Soviet target was the port of Bandar Pahlavi (today Bandar Anzali). The Iranian forces in Gilan, led by General Iranpour, made their stand at the provincial capital of Rasht and at Bandar Pahlavi, and offered a stubborn resistance. The Iranians sank barges at the entrance to Bandar Pahlavi harbour and, for lack of coastal artillery, moved a battery of 75-mm (2.95-in) guns into the area. The Iranians fought stubbornly and, despite Soviet superiority, prevented a landing. The Iranians were careful to use their artillery while Soviet aircraft were overhead, and thereby escaped detection. Soviet aircraft were engaged with modest success by 47-mm anti-aircraft guns mounted on barges.

On the following day, however, the Soviet air forces stepped up their efforts, and began heavy bomber attacks on military positions and civilian targets throughout Gilan, including Bandar Pahlavi and Rasht. At least 200 civilians were killed during the bombings. The bombings also destroyed many Iranian positions, and resistance was finally crushed by the 44^th Army, which advanced and captured both cities. The fighting was intense, and it was here that the Soviets took their heaviest casualties of the campaign. However, lacking armour and air power, the Iranians were essentially powerless to check the Soviets, and on 28 August were forced to surrender. Some Iranian forces refused to accept defeat, though, and retreated to Ramsar to continue the fight. Their efforts were undercut when the Iranian government announced a ceasefire on the following day. By that time, the Soviet forces had reached Chalus, which meant that they could cross the Chalus highway and advance on Tehran across the Alborz mountains.

Meanwhile, the Soviet forces were moving south from Iranian Azerbaijan. The 47^th Army had been delayed in the Jolfa area when three Iranian soldiers managed to block an important bridge until they ran out of ammunition and were killed. The 47^th Army then took Dilman, 80 miles (130 km) to the west of Tabriz, and captured Urmia (Oromiyeh), ostensibly to block the escape of 'German agents'. Urmia was defended by only a few snipers, to whose efforts the Soviets responded by bombing targets in the city, killing more than 12 persons and wounding many others, and much of the city’s bazaar was destroyed by fire.

At much the same time the 53^rd Army moved south from Ardabil toward the highway linking Tehran, Karaj and Tabriz, capturing Meyaneh (Mianeh) and moving to the south-east in the direction of Qazvin and Tehran by 27/28 August. The Soviets had already bypassed and then defeated the Iranian 15^th Division and 3^rd Division, and now met only sporadic resistance. The Soviet armoured spearhead drove down the highway, and was poised to take Qazvin, some 95 miles (155 km) from Tehran, on 29 August, to be followed by Saveh and Qom, to the south of Tehran, thereby cutting the main highway linking Tehran, Saveh and the Persian Gulf, so cutting Iran into two segments. But the Iranians accepted the ceasefire on 29 August, and the Soviets entered what was now an open city on 30 August. At the same time, elements of the 53^rd Army captured Hamadan, where sporadic resistance was swiftly overwhelmed. The Soviets brought their advance to a halt on 1 September and moved no farther toward Tehran from Qazvin as negotiations with the Iranian government were begun.

On 25 August, the Soviets invaded north-eastern Iran from Soviet Turkmenistan, but details of this part of the Soviet invasion are very limited. The invasion force had to cross mountainous terrain, and its goal was the city of Mashhad, Iran’s second largest city. The defence of Mashhad and Khorasan province was the responsibility of the 8,000 men of the Iranian 9^th Division, which was not motorised. It was therefore unlikely from the start that they could hold against the more numerous Soviet forces, which had armour and air support. Soviet aircraft bombed the airfield at Mashhad, destroying many Iranian fighter aircraft, along with numerous military barracks. The Soviet forces advanced in three columns across the border. There was heavy fighting for three days, and by the 28 August the Iranians had been driven back after taking heavy casualties. Mashhad fell to the Soviets on the same day.

By 28/29 August, the Iranian military situation was complete chaotic. The Allies had complete air supremacy over the skies of Iran, and large sections of the country were in their hands. Major Iranian cities, including Tehran, were suffering repeated but light air raids. Over Tehran, where casualties had been few, Soviet aircraft dropped leaflets to warn the population of an imminent major bombing attack and urge a surrender which would forestall destruction. Tehran’s population was short of food and water, and the defence forces had fled in fear of a Soviet massacre. Faced with a situation of total collapse, all the royal family but the shah and the crown prince fled to Isfahan.

The rapid collapse of the army on which Reza Shah had expended so much time and money was an Iranian humiliation. Many of the military generals had behaved with either incompetence or cowardice, and others were secret British sympathisers and sabotaged the Iranian resistance. In such circumstances it was hardly surprising that a number of generals met in secret to discuss surrender options. When he learned of this, the shah beat the head of the armed forces, General Ahmad Nakhjavan, around the head with a cane, and physically stripped him of his rank. Nakhjavan was nearly shot by the shah on the spot, but at the urging of the crown prince, was instead sent to prison. The shah ordered the resignation of Ali Mansur, the pro-British prime minister, whom he blamed for demoralising the military, and the new prime minister was Mohammad Ali Foroughi, a former prime minister. Recognising the futility of continued resistance, however, the shah ordered the Iranian military to end its resistance and ordered a ceasefire as he entered into negotiations with the British and Soviets.

Foroughi was an opponent of the shah, who had forced him into retirement in 1935 for political reasons, and had his son executed by firing squad. Entering negotiations with the British, instead of a negotiating a favourable settlement, Foroughi implied that both he and the Iranian people wished to be 'liberated' from the shah’s rule. The British and Foroughi agreed that in order for the Allies to withdraw from Iran, the Iranians would have to ensure that the German ambassador and his staff left Iran, that the German, Italian, Hungarian and Romanian legations should close, and that all remaining German nationals (including all families) be handed over to the British and Soviet authorities. The last order implied almost certain imprisonment or, in the case of those surrendered to the Soviets, possible death. Reza Shah delayed on the last demand, and planned the secret evacuation of all German nationals from Iran. By 18 September most German nationals had escaped across the border into Turkey.

The Soviet response to the shah’s prevarication came on 16 September, when they moved to occupy Tehran. Fearing execution by the communists, many of the city’s people, and especially those of wealth, fled. In a letter hand-written by Foroughi, Reza Shah announced his abdication as the Soviets entered the city on 17 September. The British wanted to restore the previous Qajar dynasty to power as it had served British interests well in the periods before Reza Shahs rise to power. But the Qajar heir to the throne, Hamid Hassan Mirza, was a British citizen who spoke no Farsi. With the support of Foroughi, therefore, Crown Prince Mohammad Reza Pahlavi took the oath to become the new shah. Reza Shah was arrested before he could leave Tehran and placed in British custody. He was sent into exile in South Africa, where he died in July 1944.

The Allies withdrew from Tehran on 17 October, but Iran was effectively divided between the UK and the USSR for the rest of World War II, the Soviets occupying northern Iran and the British not moving any further to the north than Hamadan and Qazvin.

With this crucial supply route now open to the USSR, the so-called Persian Corridor provided for a massive flow of supplies (more than 5 million tons of matériel) primarily to the USSR, but to a more limited extent to the British in the Middle East.

The new shah signed a treaty of alliance with the UK and USSR in January 1942, and this mandated non-military Iranian assistance to the Allied war effort. Article Five of the treaty committed the Allies to leaving Iran within six months of the cessation of hostilities. In September 1943 Iran declared war on Germany, thus qualifying for membership in the United Nations Organisation. At the 'Eureka' conference in Tehran during November of the same year, US President Franklin D. Roosevelt, British Prime Minister Winston Churchill, and General Secretary Iosif Stalin reaffirmed their commitment to Iran’s independence and territorial integrity, and also displayed a willingness to extend economic assistance to Iran. The treaty laid it down that Iran was not considered to be occupied by the Allies, but to be one of the Allied powers.

The war had a very disruptive effect on Iran, however. Much of the administrative bureaucracy had been damaged by the invasion, and food and other essential items were scarce. Matters were made worse, moreover, by the fact that the Soviets appropriated most of the harvest in northern Iran, leading to food shortages. The British and Soviet occupation forces used the delivery of grain as a bargaining chip, and the food crisis was exacerbated by the British and Soviet food requirements and the use of the transport network to move military equipment. Under British pressure, the shah appointed Ahmad Qavam as prime minister, and he mismanaged the entire food supply and economy resulting, in 1942, in bread riots in Tehran and famine elsewhere. Martial law was declared. In addition, inflation increased by 450%, imposing great hardship on the lower and middle classes. Even so, there was almost no armed resistance to the occupying forces.

In 1943, US troops joined the Allied forces in Iran, and 30,000 Americans were used in the operation of the Persian Corridor. This carried between 26% and 34% of all the supplies sent to the USSR under the Lend-Lease Act. The Americans also assuaged Iranian fears of colonisation by the UK and USSR by confirming that they would respect the independence of Iran. The USA also extended Lend-Lease assistance to Iran, and helped to train the Iranian army.

There were two notable German attempts to undertake operations against the Allies in Iran during 1943. In the summer the Abwehr launched 'Franz' in an attempt to use the dissident Qashqai people in Iran to sabotage the flow of British and US supplies to the USSR. 'Weitsprung' was another unsuccessful German plot, in this instance to assassinate the 'big three' Allied leaders (Stalin, Churchill and Roosevelt) at the 'Eureka' conference.

During the years of Allied occupation, Stalin expanded Soviet political influence in Azerbaijan and the Kurdish area in north-western Iran, and within the main body of Iran promoted the establishment of the communist Tudeh Party of Iran. The Soviets attempted during their occupation to embitter still further the existing tensions between tenant farmers and land owners. On 12 December 1945, after weeks of violent clashes, a Soviet-backed separatist People’s Republic of Azerbaijan was founded, and a Kurdish People’s Republic was also established late in 1945. Iranian government troops sent to re-establish control were blocked by Soviet units.

When the deadline for the Allied withdrawal arrived on 2 March 1946, six months after the end of World War II, the British began to withdraw, but the Soviets refused to do so, citing supposed threats to Soviet security. Soviet troops did not withdraw from Iran proper until May 1946, following Iran’s official complaint to the newly formed UN Security Council: this was the first complaint filed by a country in the UN’s history, and a test for the UN’s capacity to resolve global issues in the aftermath of World War II. However, the Security Council took no direct steps to pressure the Soviets to withdraw.