"At the outbreak of World War II, Iran declared its neutrality, but the country was soon invaded by both Britain and the Soviet Union. Britain had been annoyed when Iran refused Allied demands that it expel all German nationals from the country. When Hitler invaded the Soviet Union in 1941, the Allies urgently needed to transport war matériel across Iran to the Soviet Union, an operation that would have violated Iranian neutrality. As a result, Britain and the Soviet Union simultaneously invaded Iran on August 26, 1941, the Soviets from the northwest and the British across the Iraqi frontier from the west and at the head of the Persian Gulf in the south. Resistance quickly collapsed. Reza Shah knew the Allies would not permit him to remain in power, so he abdicated on September 16 in favor of his son, who ascended the throne as Mohammad Reza Shah Pahlavi. Reza Shah and several members of his family were taken by the British first to Mauritius and then to Johannesburg, South Africa, where Reza Shah died in July 1944.
The occupation of Iran proved of vital importance to the Allied cause and brought Iran closer to the Western powers. Britain, the Soviet Union, and the United States together managed to move over 5 million tons of munitions and other war matériel across Iran to the Soviet Union. In addition, in January 1942 Iran signed a tripartite treaty of alliance with Britain and the Soviet Union under which Iran agreed to extend nonmilitary assistance to the war effort. The two Allied powers, in turn, agreed to respect Iran's independence and territorial integrity and to withdraw their troops from Iran within six months of the end of hostilities. In September 1943, Iran declared war on Germany, thus qualifying for membership in the United Nations (UN). In November at the Tehran Conference, President Franklin D. Roosevelt, Prime Minister Winston Churchill, and Prime Minister Josef Stalin reaffirmed a commitment to Iran's independence and territorial integrity and a willingness to extend economic assistance to Iran.
The effects of the war, however, were very disruptive for Iran. Food and other essential items were scarce. Severe inflation imposed great hardship on the lower and middle classes, while fortunes were made by individuals dealing in scarce items. The presence of foreign troops accelerated social change and also fed xenophobic and nationalist sentiments. An influx of rural migrants into the cities added to political unrest. The Majlis, dominated by the propertied interests, did little to ameliorate these conditions. With the political controls of the Reza Shah period removed, meanwhile, party and press activity revived. The communist Tudeh Party was especially active in organizing industrial workers. Like many other political parties of the left and center, it called for economic and social reform.
Eventually, collusion between the Tudeh and the Soviet Union brought further disintegration to Iran. In September 1944, while American companies were negotiating for oil concessions in Iran, the Soviets requested an oil concession in the five northern provinces. In December, however, the Majlis passed a law forbidding the government to discuss oil concessions before the end of the war. This led to fierce Soviet propaganda attacks on the government and agitation by the Tudeh in favor of a Soviet oil concession. In December 1945, the Azarbaijan Democratic Party, which had close links with the Tudeh and was led by Jafar Pishevari, announced the establishment of an autonomous republic. In a similar move, activists in neighboring Kordestan established the Kurdish Republic of Mahabad. Both autonomous republics enjoyed the support of the Soviets, and Soviet troops remaining in Khorasan, Gorgan, Mazandaran, and Gilan. Other Soviet troops prevented government forces from entering Azarbaijan and Kordestan.
Soviet pressure on Iran continued as British and American troops evacuated in keeping with their treaty undertakings. Soviet troops remained in the country. Prime Minister Ahmad Qavam had to persuade Stalin to withdraw his troops by agreeing to submit a Soviet oil concession to the Majlis and to negotiate a peaceful settlement to the Azarbaijan crisis with the Pishevari government. In April the government signed an oil agreement with the Soviet Union; in May, partly as a result of United States, British, and UN pressure, Soviet troops withdrew from Iranian territory. Qavam took three Tudeh members into his cabinet. Qavam was able to reclaim his concessions to the Soviet Union, however. A tribal revolt in the south, partly to protest communist influence, provided an opportunity to dismiss the Tudeh cabinet officers. In December, ostensibly in preparation for new Majlis elections, he sent the Iranian army into Azarbaijan. Without Soviet backing, the Pishevari government collapsed, and Pishevari himself fled to the Soviet Union. A similar fate befell the Kurdish Republic of Mahabad. In the new Majlis, a strong bloc of deputies, organized in the National Front and led by Mohammad Mossadeq, helped defeat the Soviet oil concession agreement by 102 votes to 2. The Majlis also passed a bill forbidding any further foreign oil concessions and requiring the government to exploit oil resources directly.
Soviet influence diminished further in 1947, when Iran and the United States signed an agreement providing for military aid and for a United States military advisory mission to help train the Iranian army. In February 1949, the Tudeh was blamed for an abortive attempt on the shah's life, and its leaders fled abroad or were arrested. The party was banned."
