Following the rise of the Pahlavi dynasty in 1925 the new Imperial Iranian Army became a priority. By 1941 the army stood at 125,000 troops—five times its original size—and was considered well trained and well equipped. However, the Iranian Army was focused on internal security operations, rather than, Farrokh says 'rather than fighting well-led and equipped Soviet and Western armies.'[5]
In 1941 the Soviets and British launched the Invasion of Iran (1941), which took place from 25 August to 17 September. London and Moscow had insisted that the shah expel Iran's large German population and allow shipments of war supplies to cross the country en route to the Soviet Union. Both of these proved unacceptable to Reza Shah; he was sympathetic to Germany, and Iran had declared its neutrality in the Second World War. Iran's location was so strategically important to the Allied war effort, however, that London and Moscow chose to overlook Tehran's claim of neutrality. From the south came the British Paiforce, under the command of Lieutenant-General Edward Quinan. Paiforce was made up of the 8th and 10th Indian Infantry Divisions, plus three other brigades. Meanwhile, the Soviets invaded from the north. Three armies, the 44th, 47th and 53rd Armies of the Transcaucasian Front under General Dmitry Timofeyevich Kozlov, occupied Iran's northern provinces. In response to the invasion, the Iranian Army mobilised nine infantry divisions.
Against the Allied forces, the Iranian army was overwhelmed in three days, while the fledgling Iranian air force and navy suffered heavy damage. Conscripts deserted by the thousands. His institutional power base ruined, Reza Shah abdicated in favor of his young son, Mohammad Reza Shah Pahlavi. In the absence of a broad political power base and with a shattered army, Mohammad Reza Shah faced an almost impossible task of rebuilding.[4] There was no popular sympathy for the army in view of the widespread and largely accurate perception that it was a brutal tool used to uphold a dictatorial regime. The young shah, distancing Tehran from the European military, in 1942 invited the United States to send a military mission to advise in the reorganization effort. With American advice, emphasis was placed on quality rather than quantity.
The small but more confident army that resulted from American training was capable enough to participate in the 1946 campaign in Azarbaijan to put down a Soviet-inspired separatist rebellion. During the three years of occupation, Stalin had expanded Soviet political influence in Azerbaijan and the Kurdish area in northwestern Iran. On 12 December 1945, after weeks of violent clashes a Soviet-backed separatist People's Republic of Azerbaijan was founded. The Kurdish People's Republic was also established in late 1945. Iranian troops sent to reestablish control were blocked by Soviet Red Army units. When the deadline for withdrawal arrived on 2 March 1946, six months after the end of hostilities, the British began to withdraw, but Moscow refused, "citing threats to Soviet security," sparking the Iran crisis of 1946. Soviet troops did not withdraw from Iran proper until May 1946, following Iran's official complaint to the newly formed United Nations Security Council.
Unlike its 1925 counterpart, the 1946 Majlis was suspicious of the shah's plans for a strong army.[4] Many members of the parliament feared that the army would once again be used as a source of political power. To curtail the shah's potential domination of the country, they limited his military budgets.
Dramatic reforms brought in a host of western advisors and over the course of more than three decades the army was to become the world's fifth strongest by 1979. Throughout the 1970s the Imperial Iranian Ground Forces, as they were then known, underwent a rapid transformation and increase in strength.
In the early 1970s the Sultan of Oman was fighting the Dhofar Rebellion with British support. As a result of Sultan Qaboos's diplomatic initiatives, the Shah sent a brigade of troops numbering 1,200 and with its own helicopters to assist the Sultan's Armed Forces in 1973. The Iranian brigade first secured the Salalah-Thumrait road. In 1974, the Iranian contribution was expanded into the Imperial Iranian Task Force, numbering 4,000. They attempted to establish another interdiction line, codenamed the "Damavand Line", running from Manston, a few miles east of Sarfait, to the coast near the border with South Yemen (the PDRY). Heavy rebel opposition, which included artillery fire from within South Yemen, thwarted this aim for several months. Eventually, the town of Rahkyut, which the PFLO had long maintained as the capital of their liberated territory, fell to the Iranian task force.[6] The IITF remained in Oman in December 1975, then at a strength of 3,000.[7]
Insignia of the Islamic Republic of Iran Army Ground Force
In 1979 the Army was a largely mechanised and armoured force of about 285,000 troops; Organised in 3 corps, with headquarters in Tehran area, in Shiraz in the south, and in Kermanshah near the Iraq border. There were additional plans for a fourth corps to be established at the Chah Bahar complex at the eastern end of the Persian Gulf.[8]
Its major ground formations included the following:
Three armoured divisions (plus one more being organised in Sistan Baluchestan, possibly the 88th Armoured Division): each with six tank battalions and five mechanised infantry battalions,
Three infantry divisions,
Two Iranian Imperial Guard Divisions and
Four independent brigades (1 armoured, 1 infantry, 1 airborne and 1 Special Forces)
Army Aviation Command with 200 plus helicopters.
These combat units, backed up by the usual complement of support units, were said to be 85 percent operational