1979
Al-Bakr resigns; his vice-president, Saddam Hussein, succeeds him (July 16). Hussein swiftly executes political rivals.
1980
The bloody eight-year Iran-Iraq war begins. The main issue is control of the Shatt al Arab waterway, an essential resource providing for water and transportation that runs along the border of both countries (Sept. 22).
THE CHRONIC 'RUB' BETWEEN IRAN AND IRAQ and the rest of the region has always been access to water rights for shipping and commerce. It was the trouble during the Iran-Iraq war as well as the hatred that exists between Sunni and Shia. Iran is/was Shia and Iraq under Saddam was under Sunni influence.
Additionally, the invasion into Kuwait that Bush 41 faced was for the same reason. Water rights for shipping and commerce. Although, by now that was getting to be more of an excuse than a reason. See, Kuwait is Shia as well.