The Iran–Iraq War, also called the First Imposed War, Eight-Year War, or Sacred Defense by Iran, began with the Iraqi invasion of Iran in September 1980. After eight years of conflict, both countries accepted a ceasefire deal brokered by the United Nations, which became effective in August 1988. The war caused around 500,000 deaths (excluding numbers from the related Anfal campaign), making it the deadliest conventional war ever fought between regular armies of developing countries.
In starting the war, the Iraqi government—led by President Saddam Hussein—primarily wanted to prevent Ruhollah Khomeini, Iran's leader following the 1979 Iranian Revolution, from exporting Iran's new state ideology to Iraq. Iraq also feared that Iran, being a theocratic state mostly composed of Shia Muslims, would rally Iraq's Shia majority against the Sunni Muslim-controlled Baʽathist government. Iraq also wished to replace Iran as the main national power in the Persian Gulf. The war followed a long-running history of border disputes between the two states, as a result of which Iraq planned to retake the eastern bank of the Shatt al-Arab river that it had ceded to Iran in the 1975 Algiers Agreement.
The conflict involved large-scale trench warfare, and deliberate attacks on civilians, including Iraqi chemical attacks. At the start of the war, Iraq expected a decisive victory, considering Iran's post-revolutionary chaos, but their invasion had stalled by December 1980. The Iranian military then gained momentum, and recaptured all their territory by June 1982. Having pushed Iraqi forces back to the pre-war borders, Iran launched an invasion of Iraq, which created a five-year offensive. In mid-1988, Iraq launched a series of counter-offensives that created the military stalemate present at the war's end.
Iraq was aided by the National Council of Resistance of Iran, the United States, the United Kingdom, the Soviet Union, France, Italy, Yugoslavia, and most Arab countries. Iran was aided by the Kurdistan Democratic Party, the Patriotic Union of Kurdistan, Syria, Libya, North Korea, China, South Yemen, Pakistan, Cuba, and Israel. Meanwhile, Iraqi support for Arab separatists in Iran increased.
After years of military and economic losses, decreasing morale, intensifying Iran–U.S. relations, and little international action against Iraqi attacks on Iranian civilians, Iran agreed to a ceasefire with Iraq under United Nations Security Council Resolution 598. The war did not create any permanent border changes, and neither country received war reparations afterwards. Both sides suffered financially. They continued engaging in low-level military conflict until relations improved following Saddam's overthrow in 2003.
Background
Iran–Iraq relations
In 1937, Iran and Iraq signed a treaty to settle their dispute over control of the Shatt al-Arab river; they agreed that Iranian ships had to pay tolls when they used the river. In 1969, Iran broke the treaty, as their ships no longer paid the tolls. The Shah of Iran argued that the treaty had been unfair. Iraq threatened war, but did nothing at this time, as their weaker military became threatened when Iranian naval forces sailed down the Shatt al-Arab in a show of force. The new Iraqi–Iranian tensions led to significant bloodshed, which lasted until the 1975 Algiers Agreement, when Iraq ceded to Iran the eastern bank of the river. Their relations briefly improved in 1978, when Iranian agents in Iraq discovered plans for a pro-Soviet coup d'état against Iraq's government. When informed of this plot, Iraq's president Saddam Hussein ordered the execution of dozens of his army's officers, and expelled Ruhollah Khomeini from Iraq, who led clerical opposition to the Shah.
After the Iranian Revolution
Tensions between Iraq and Iran were fuelled by Iran's Islamic revolution and its appearance of being a Pan-Islamic force, in contrast to Iraq's Arab nationalism. Despite Iraq's goal of regaining the Shatt al-Arab, the Iraqi government initially seemed to welcome the Iranian revolution, which overthrew Shah Mohammad Reza Pahlavi, who was seen as a common enemy. There were frequent clashes along the Iran–Iraq border throughout 1980.
Khomeini called on Iraqis to overthrow the Ba'ath government, which was received with considerable anger in Baghdad. In July 1979, despite Khomeini's call, Saddam gave a speech praising the Iranian Revolution and called for an Iraqi–Iranian friendship based on non-interference in each other's internal affairs. When Khomeini rejected Saddam's overture by calling for Islamic revolution in Iraq, Saddam was alarmed. Iran's new Islamic administration was regarded in Baghdad as an irrational, existential threat to the Ba'ath government, especially because the Ba'ath party, having a secular nature, discriminated against and posed a threat to the fundamentalist Shia movement in Iraq, whose clerics were Iran's allies within Iraq and whom Khomeini saw as oppressed.
In April 1980, the Islamic Dawa Party, an Iraqi Islamist group with supportive ties to Iran, attempted to assassinate Tariq Aziz, a high ranking Ba'athist and Iraq's deputy prime minister, in retaliation for a March decree declaring "membership of Dawa [to be] a capital offense". The attempt failed and instead killed several students. Three days later, the funeral procession for the dead students was bombed. This failed assassination plot, carried out by an Iran-backed group, formed a part of Iraq's casus belli for the invasion of Iran. Iraq's immediate response was to order the execution of Muhammad Baqir al-Sadr, an Iraqi Shi'ite cleric seen as the public face of the Dawa movement, along with al-Sadr's sister. On 30 April, Iraq organised an attack on the Iranian embassy in London.
Saddam's primary interest in war may have also stemmed from his desire to right the supposed "wrong" of the Algiers Agreement, in addition to finally achieving his desire of becoming the regional superpower. Saddam's goal was to supplant Egypt as the "leader of the Arab world" and to achieve hegemony over the Persian Gulf. He saw Iran's increased weakness due to revolution, sanctions, and international isolation. Saddam had invested heavily in Iraq's military since his defeat against Iran in 1975, buying large amounts of weaponry from the Soviet Union and France. Between 1973 and 1980, Iraq purchased numerous tanks and Soviet-made aircraft.
By 1980, Iraq possessed 242,000 soldiers, second only to Egypt in the Arab world, 2,350 tanks and 340 combat aircraft. Watching the disintegration of the Iranian army, he saw an opportunity to attack, using the threat of Islamic Revolution as a pretext. Iraqi military intelligence reported in July 1980 that despite Iran's bellicose rhetoric, "it is clear that, at present, Iran has no power to launch wide offensive operations against Iraq, or to defend on a large scale." Days before the Iraqi invasion and in the midst of rapidly escalating cross-border skirmishes, Iraqi military intelligence again reiterated on 14 September that "the enemy deployment organization does not indicate hostile intentions and appears to be taking on a more defensive mode".
On 8 March 1980, Iran announced it was withdrawing its ambassador from Iraq, downgraded its diplomatic ties to the charge d'affaires level, and demanded that Iraq do the same. The following day, Iraq declared Iran's ambassador persona non grata, and demanded his withdrawal from Iraq by 15 March.
Iranian military preparations
In Iran, severe officer purges, including numerous executions ordered by Sadegh Khalkhali, the new Revolutionary Court judge, and shortages of spare parts for Iran's American and British-made equipment had crippled Iran's once-mighty military. Between February and September 1979, Iran's government executed 85 senior generals and forced many other generals into early retirement.
By September 1980, some 12,000 officers had been purged from all levels from the army. This reduced the Iranian military's operational capacities.
On the eve of the revolution in 1978, international experts in military science had deemed Iran's armed forces the world's fifth most powerful. However, by the eve of war with Iraq, the recently formidable Iranian army was in many crucial ways a shell of its former self, having been badly weakened by losses in experienced personnel. The desertion rate had reached 60%, the officer corps was devastated and its most highly skilled soldiers and aviators had been exiled, imprisoned, or executed. When the invasion occurred, many pilots and officers were released from prison, or had their executions commuted to combat the Iraqis. Throughout the war, Iran never managed to fully recover from this flight of human capital.
Many junior officers were promoted to generals, resulting in the army being more integrated as a part of the regime by the war's end. Meanwhile, a new paramilitary organisation gained prominence in Iran, the Islamic Revolutionary Guard Corps (IRGC). Created to protect the new regime and serve as a counterbalance to the army, the IRGC had been trained to act only as a militia and struggled to adapt as needed following the Iraqi invasion, initially refusing to fight alongside the regular army, resulting in many defeats. It was not until 1982 that the two groups began carrying out combined operations.
The Basij paramilitary was founded in response to the invasion. They were poorly armed, and had members as young as 12 and as old as 70. Subordinate to the Revolutionary Guard, they made up most of the manpower that was used in the Guard's attacks.
Despite neglect by the new regime, at the war's outset, Iran still had at least 1,000 tanks and several hundred functional aircraft, and could cannibalise equipment to procure spare parts. Continuous sanctions greatly limited Iran from acquiring many additional heavy weapons, including tanks and aircraft.
Iraqi military preparations
In addition, the area around the Shatt al-Arab posed no obstacle for Iraqi river-crossing equipment. Iraq correctly deduced that Iran's defences at the crossing points around the Karkheh and Karoun Rivers were undermanned and that the rivers could be easily crossed. Iraqi intelligence was also informed that the Iranian forces in Khuzestan province, which consisted of two divisions prior to the revolution, now only consisted of several ill-equipped and under-strength battalions with only a handful of operational company-sized tank units.
The only qualms the Iraqis had were over the Iran Air Force. Despite the purge of several key pilots and commanders, as well as the lack of spare parts, the air force showed its power during local uprisings and rebellions. They were also active after the failed U.S. attempt to rescue its hostages, Operation Eagle Claw. Based on these observations, Iraq's leaders decided to carry out a surprise airstrike against the Iranian air force's infrastructure prior to the main invasion.
Khuzestan
It is believed that Iraq sought to either annex, or establish suzerainty over, Iran's Khuzestan province, but Saddam Hussein publicly denied this in November 1980.
Border conflicts leading up to the war
On 10 September 1980, Iraq forcibly reclaimed territories in Zain al-Qaws and Saif Saad that it had been promised under the terms of the 1975 Algiers Agreement but that Iran had never handed over, leading to both Iran and Iraq voiding the treaty, on 14 and 17 September, respectively. As a result, the only outstanding border dispute between Iran and Iraq at the time of the Iraqi invasion of 22 September was the question of whether Iranian ships would fly Iraqi flags and pay Iraq navigation fees for a stretch of the Shatt al-Arab spanning several miles.
Course of the war
1980: Iraqi invasion
Iraq launched a full-scale invasion of Iran on 22 September 1980. The Iraqi Air Force launched surprise air strikes on ten Iranian airfields with the objective of destroying the Iranian Air Force. The attack failed to cripple the Iranian Air Force: while it damaged some of Iran's airbase infrastructure, it did not destroy a significant number of aircraft. The Iraqi Air Force was only able to strike in depth with a few aircraft, and Iran had built hardened aircraft shelters where most of its combat aircraft were stored.
The next day, Iraq launched a ground invasion, mounting three simultaneous attacks along a 644 km (400 mi) front. Saddam hoped an attack on Iran would lead to the new government's downfall, or at least end Iran's calls for his overthrow.
Four Iraqi divisions were sent to Khuzestan near the border's southern end, to cut off the Shatt al-Arab from the rest of Iran and to establish a territorial security zone. Two other divisions invaded across the border's north and center to prevent an Iranian counter-attack. Two of the four Iraqi divisions, one mechanised and one armoured, operated near the southern end and besieged the strategically important port cities of Abadan and Khorramshahr.
The two armoured divisions secured the territory bounded by the cities of Khorramshahr, Ahvaz, Susangerd, and Musian. On the central front, the Iraqis occupied Mehran, advanced towards the Zagros Mountains, and were able to block the traditional Tehran–Baghdad invasion route by securing territory forward of Qasr-e Shirin, Iran. On the northern front, the Iraqis attempted to establish a strong defensive position opposite Suleimaniya to protect the Iraqi Kirkuk oil complex. Iraqi hopes of an uprising by the Arabs of Khuzestan failed to materialise, as most of the Arabs remained loyal to Iran.
Patrick Brogan described the Iraqi troops advancing into Iran in 1980 as "badly led and lacking in offensive spirit". The first known chemical weapons attack by Iraq on Iran probably took place during the fighting around Susangerd. Iraqi Minister of Defence Adnan Khayr Allah played a crucial role in rebuilding and modernising the Iraqi military.
Though the Iraqi air invasion surprised the Iranians, their air force retaliated the day after with a large-scale attack against Iraqi air bases and infrastructure in Operation Kaman 99. Groups of fighter jets attacked targets throughout Iraq, such as oil facilities, dams, petrochemical plants, and oil refineries, and included Mosul Airbase, Baghdad, and the Kirkuk oil refinery. Iraq was taken by surprise at the strength of the retaliation, which inflicted heavy losses and economic disruption, but Iraqi air defences also inflicted heavy losses.