An eight-year Gulf war killed hundreds of thousands for no border change
Iraq invaded Iran in September 1980; a UN-brokered ceasefire took effect in August 1988 after roughly half a million deaths excluding wider tallies. Saddam Hussein sought to block Khomeini's post-1979 ideology from rallying Iraq's Shia majority against Baathist Sunni rule.
The quarrel over the Shatt al-Arab river ran back decades. A 1937 treaty made Iranian ships pay tolls on the waterway; in 1969 the shah repudiated it as unfair and sent naval vessels down the river, and Iraq, militarily weaker, backed off. Clashes continued until the 1975 Algiers Agreement handed Iran the eastern bank, a concession Saddam Hussein reportedly wanted to reverse. He had spent heavily on Soviet and French arms since then, and by 1980 Iraq had about 242,000 soldiers, 2,350 tanks and 340 combat aircraft.
The revolution in Tehran changed the calculation. Baghdad at first welcomed the fall of the shah, and in July 1979 Saddam publicly proposed friendship based on mutual non-interference, but Khomeini urged Iraqis to topple the Ba'ath government. In April 1980 the Iran-linked Dawa Party tried to kill deputy prime minister Tariq Aziz, killing several students instead; Iraq executed the cleric Muhammad Baqir al-Sadr, and the two countries had already downgraded diplomatic ties in March.
Iran looked vulnerable. Between February and September 1979 the new government executed 85 senior generals, many on orders of the revolutionary judge Sadegh Khalkhali, and its American and British equipment lacked spare parts. Iraqi intelligence reported that summer that Iran could neither mount large offensives nor defend on a large scale. The invasion nevertheless bogged down, and after retaking its land Iran pressed a five-year offensive into Iraq before Iraqi counterattacks in mid-1988 produced stalemate.
The toll was staggering for a conventional war between developing states, and the fighting included trench warfare and Iraqi chemical attacks on civilians. Low-level hostility persisted after the ceasefire, and relations improved only after Saddam was overthrown in 2003.
Source: Iran–Iraq War
