The Iran-Iraq War of 1980-88 was the longest conventional war between sovereign states in the 20th century. As a war it was grimly retrograde, consisting for the most part of static, positional infantry warfare, not unlike the Western Front during World War I. The war was launched by Iraq on September 22, 1980, following an Iranian refusal to abandon boundary concessions on the Shatt-al-Arab waterway that Iran had secured in a 1975 treaty (Pelletiere, 1992, p. 34). After two years of fighting on the defensive, Iran went over to the offensive, but made little more progress than Iraq had. Technically the war ended by negotiated settlement; in practice it simply ran down (Pelletiere, 1992, pp. 146-48). The following essay will concentrate on the alternatives faced by each of the rival powers in the 1980 crisis that led to the war, and Iraq's decision to resort to military force.
Conflict between Iran and Iraq has deep historical roots. The Tigris and Shatt-al-Arab rivers form a natural boundary between two distinct geographical and climatological regions: to the west, the low-lying,irrigable Tigris-Euphrates valley; to the east, the more mountainous Iranian upland. This distinction was formative of the earliest periods of recorded history, when the Sumerian and later civilizations of Mesopotamia -- which corresponds roughly to modern Iraq -- periodically faced "barbarian" incursions from the Iranian plateau to the east, and at a later date were conquered by the Persian Empire. (The Shatt-al-Arab, formed by the confluence of the Tigris and Euphrates, did not exist in antiquity, when the Gulf extended farther to the north than at present; alluvial deposits gradually filled in the shallow sea.)
The expansion of Islam in the seventh century through both Mesopotamia and Persia did not eliminate the distinction of the two regions. Though politically unified under the Caliphate, this unity evaporated when the Caliphate fragment...