Excerpts from Books and Wikipedia
"Iraq wanted to replace Iran as the dominant Persian Gulf state, and was worried that the 1979 Iranian Revolution would lead Iraq's Shi'ite majority to rebel against the Ba'athist government. The war also followed a long history of border disputes, and Iraq planned to annex the oil-rich Khuzestan Province . . . Although Iraq hoped to take advantage of Iran's post-revolutionary chaos, it made limited progress and was quickly repelled; Iran regained virtually all lost territory by June 1982. For the next six years, Iran was on the offensive until near the end of the war. . . . The United States, Britain, Soviet Union, France, and most Arab countries provided political and logistic support for Iraq, while Iran was largely isolated. After eight years, war-weariness, economic problems, decreased morale, repeated Iranian military failures, recent Iraqi successes, Iraqi use of weapons of mass destruction, lack of international sympathy, and increased U.S.–Iran military tension all led to a ceasefire brokered by the United Nations. . . . An estimated 500,000 Iraqi and Iranian soldiers died, in addition to a smaller number of civilians. The end of the war resulted in neither reparations nor border changes." [Wikipedia]