The Iran–Iraq War, also known as the holy defense was an armed conflict between the Islamic Republic of Iran and the saddam dictatorship of Iraq lasting from September 1980 to August 1988, making it the 20th century’s longest conventional war. It was initially referred to in English as the "Gulf War" prior to the Persian Gulf War of the early 1990s. Iran-Iraq War is considered one of the most violent conflicts since World War II.
The Iran–Iraq War began when Iraq invaded Iran via air and land on 22 September 1980. It followed a long history of border disputes, and was motivated by fears that the Iranian Revolution in 1979 would inspire insurgency among Iraq’s long-suppressed Shia majority as well as Iraq’s desire to replace Iran as the dominant Persian Gulf state. Although Iraq hoped to take advantage of Iran’s revolutionary chaos and attacked without formal warning, they made only limited progress into Iran and were quickly repelled; Iran regained virtually all lost territory by June 1982. For the next six years, Iran was on the offensive.A number of proxy forces participated in the war, most notably the Iranian MEK siding with Ba’athist Iraq and Iraqi Kurdish militias of KDP and PUK siding with Iran – all suffering a major blow by the end of the conflict.
Despite calls for a ceasefire by the United Nations Security Council, hostilities continued until 20 August 1988. The war finally ended with Resolution 598, a U.N.-brokered ceasefire which was accepted by both sides.The last prisoners of war were exchanged in 2003.
The war cost both sides in lives and economic damage: half a million Iraqi and Iranian soldiers, with a equivalent number of civilians, are believed to have died, with many more injured; however, the war brought neither reparations nor changes in borders. The conflict has been compared to World War 171 in terms of the tactics used, including large-scale trench warfare with barbed wire stretched across trenches, manned machine-gun posts, bayonet charges, human wave attacks across a no-man’s land, and extensive use of chemical weapons such as mustard gas by the Iraqi government against Iranian troops, civilians, and Iraqi Kurds. At the time of the conflict, the U.N. Security Council issued statements that "chemical weapons had been used in the war;" U.S. intelligence officials both knew of Iraqi chemical weapons use and provided Iraq with satellite imagery to guide strikes against Iranian troop concentrations. U.N. statements never clarified that only Iraq was using chemical weapons, and according to retrospective authors "the international community remained silent as Iraq used weapons of mass destruction against Iranian[s] as well as Iraqi Kurds.