In April 1969, Iran abrogated the 1937 treaty over the Shatt al-Arab, leading to heightened tensions with Iraq. The move marked the beginning of a period of conflict and territorial disputes between the two countries.

The Algiers Agreement of 1975 settled border disputes between Iran and Iraq, but tensions persisted as Iraq sought to retake the eastern bank of the Shatt al-Arab. The agreement was a temporary resolution that did not address deeper territorial ambitions.

In 1978, relations between Iran and Iraq briefly improved when Iranian agents uncovered a pro-Soviet coup plot in Iraq. This event led to a temporary reconciliation between the two countries, but underlying tensions remained unresolved.

On July 17, 1979, Saddam Hussein gave a speech praising the Iranian Revolution and called for Iraqi-Iranian friendship based on non-interference in internal affairs. However, Ayatollah Khomeini's rejection of this overture led to tensions between the two countries.

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.

On September 10, 1980, Iraq forcibly reclaimed territories promised under the 1975 Algiers Agreement, leading to the treaty being declared null and void by both Iran and Iraq.

On September 17, 1980, Iran declared the 1975 Algiers Agreement null and void in response to Iraq's actions of reclaiming territories promised under the agreement.

On September 22, 1980, Iraq launched a surprise invasion of Iran, marking the beginning of the Iran-Iraq War. The invasion included air assaults and ground offensives on multiple fronts.

The day after Iraq's air invasion, the Iranian air force retaliated with a large-scale attack against Iraqi air bases and infrastructure in Operation Kaman 99, causing heavy losses and economic disruption to Iraq.

On September 24, 1980, the Iranian Navy attacked Basra, Iraq, destroying two oil terminals near the Iraqi port of Al-Faw, reducing Iraq's ability to export oil.

After Iraq's failed air attack, Iranian airplanes bombed Baghdad's Osirak Nuclear Plant and other Iraqi targets. The Iranian navy also attacked Iraqi oil ports.

Iraqi forces captured the strategic city of Khorramshahr after encountering more resistance than expected in the Iran-Iraq War.

Iran launched a large-scale offensive from Dezful resulting in one of the biggest tank battles of the war, with Iranian tanks being cut off and nearly wiped out by Iraqi tanks.

Iranian air force successfully attacked Iraq's H3 airbase, dealing a significant blow to the Iraqi air force in the Iran-Iraq War.

In late 1981, Iran launched Operation Eighth-Imam to end the Iraqi Siege of Abadan. The operation involved a combined force of regular army artillery, armor, Pasdaran, and Basij infantry. Despite initial gains, Iran faced setbacks during a tank battle.

On November 29, 1981, Iran initiated Operation Tariq al-Quds, retaking the town of Bostan from Iraqi divisions. This operation marked the first use of Iranian 'human wave' tactics, leading to significant casualties on both sides.

On March 19, 1982, the Iraqis launched Operation al-Fawz al-'Azim in an attempt to preempt an Iranian attack. Despite using tanks, helicopters, and fighter jets, the Iraqi forces were unaware of the Iranian offensive preparations.

Led by Colonel Ali Sayad Shirazi, Iran launched an attack on Iraqi forces using helicopters and fighter jets, resulting in the capture of an Iraqi headquarters and the destruction of hundreds of Iraqi tanks and armored vehicles.

Iran launched an offensive after air raids on Iraq air bases, achieving air superiority and driving out Iraqi forces from Susangerd area, capturing thousands of Iraqi troops and tanks.

Iranians captured Khorramshahr from Iraq after a drive across the Karun River, resulting in the surrender of 19,000 Iraqis and heavy casualties on both sides.

Saddam Hussein proposed peace with Iran, but Khomeini rejected and announced intentions to invade Iraq during the Iran-Iraq War.

Iran launched Operation Ramadan, a large-scale attack involving over 180,000 troops, near Basra in southern Iraq. The battle saw the first major use of chemical warfare in the conflict, with Iraqis using tear gas against the attacking Iranian forces.

Iran attacked near al-Amarah with Revolutionary Guard troops, aiming to connect northern and southern Iraq, but faced obstacles and casualties.

On 23 July 1983, Iranians, with Kurdish support, captured the Iraqi town of Haj Omran during Operation Dawn-2, resisting an Iraqi poison gas counteroffensive.

On 30 July 1983, Iran attempted to sweep away Iraqi forces controlling roads between Iranian towns Mehran, Dehloran, and Elam during Operation Dawn-3, facing Iraqi airstrikes and chemical attacks.

Iran launched an offensive to reclaim disputed territory and reach the outskirts of Mandali, but was stopped by Iraqi attacks.

Iran captured part of the Bayat oilfield and destroyed Iraqi tanks and planes, but failed to capture Mandali due to Iraqi reinforcements and T-72 tanks.

In October 1984, Iran launched the Dawn 7 Offensive to recapture the city of Mehran from Iraq, which had been occupied since the beginning of the war. The offensive was successful in retaking the city.

On March 11, 1985, Iran launched Operation Badr, a major offensive directed against the Baghdad-Basra highway during the Iran-Iraq War. The operation was successful in breaking through Iraqi lines and capturing part of the highway.

Iranian forces captured the Al Faw Peninsula, cutting off Iraq from the sea in the Iran-Iraq War.

Iraq attempted to drive deep into Iran by capturing the city of Mehran, but Iranian forces recaptured the city using mountain warfare tactics, leading to heavy losses for Iraq.

Iran launched Operation Karbala-4 as a diversionary attack against Iraq, capturing the island of Umm al-Rassas in the Shatt-Al-Arab river but failing to advance further. The Iranians suffered 60,000 casualties while the Iraqis had 9,500 casualties.

Iraq began using chemical weapons on civilian targets in Iran, including mustard gas, sarin, and tabun.

In a massive air strike on Kharg Island, Iraq destroyed two supertankers but lost five aircraft to Iranian F-14 Tomcats.

On 17 April 1988, Iraq launched Operation Ramadan Mubarak against Iranian forces on the al-Faw peninsula, using chemical weapons to achieve victory. The heavy use of chemical weapons was a decisive factor in the Iraqi success.

On 25 May 1988, Iraq launched the first of five Tawakalna ala Allah Operations, involving a massive artillery barrage and the use of chemical weapons. The operation successfully expelled Iranian forces from the border town of Shalamcheh.

On 13 June 1988, Iran launched a desperate counter-attack into Iraq, infiltrating through Iraqi trenches and managing to strike Saddam's presidential palace in Baghdad. The Iranians were eventually driven back to their original positions as the Iraqis launched a significant number of air sorties.

On 18 June 1988, the People's Mujahedin of Iran conducted a military operation known as Operation Forty Stars, wiping out a Pasdaran division and seizing territory in Iran. The operation was carried out independently without Iraqi involvement.

Iraq launched a military operation against Iran on Majnoon Island, using tanks, artillery barrages, and amphibious craft. Saddam Hussein appeared on television to lead the charge, resulting in the majority of Iranian defenders being killed.

Iraq captured the city of Dehloran, 30 km inside Iran, along with a significant amount of troops, armor, and material. This capture was part of the Second Tawakal ala Allah Operation.

Commander-in-Chief Rafsanjani ordered Iranian forces to retreat from Haj Omran in Kurdistan. This retreat marked a significant moment in the war as Iran's army inside Iraq had largely disintegrated.

Iran accepted Resolution 598, signaling its willingness to accept a ceasefire and effectively ending the Iran–Iraq War. The decision was influenced by the realization of the war's toll on civilian populations and the military challenges faced by Iran.

Operation Forough Javidan was launched by Mujahadeen-e-Khalq (MEK) with the support of the Iraqi army in central Iran. The MEK advanced rapidly towards Kermanshah, seizing several towns, but failed to incite an uprising among the Iranian population.

Iranian military launched Operation Mersad to counter the MEK offensive, resulting in the defeat of the MEK forces in the city of Kerend-e Gharb.

Iran drove the MEK out of Qasr-e-Shirin and Sarpol Zahab, marking a significant victory in the conflict.

The Iranian navy fired on a freighter in the Persian Gulf, while Iraq launched chemical attacks on Iranian civilians, leading to international pressure and eventually the end of combat operations between Iran and Iraq.

Resolution 598 became effective, officially ending all combat operations between Iran and Iraq.

By 20 August 1988, peace with Iran was restored after the Iran-Iraq War.

Iraq concluded its anti-Kurd campaign by September 3, 1988, crushing all resistance and forcing Kurdish civilians to relocate.

The Iraqgate scandal in August 1989 revealed that a branch of Italy's largest bank funneled $5 billion to Iraq using U.S. taxpayer-guaranteed loans, leading to charges of illegal loans and arms purchases.

In August 1990, amidst Iraq's invasion of Kuwait, Iraq and Iran restored diplomatic relations. Iraq agreed to Iranian terms for settling the war, including the withdrawal of Iraqi troops from Iranian territory, division of sovereignty over the Shaṭṭ Al-ʿArab waterway, and a prisoner-of-war exchange.

The final exchange of prisoners between Iraq and Iran, as part of the settlement agreement reached in 1990, was completed in March 2003.

Iraqi President Jalal Talabani greets Iranian President Mahmoud Ahmadinejad during his visit to Baghdad, signifying a significant moment as it is the first time an Iranian president has visited since the Iran-Iraq War in the 1980s.