On 22 September 1980, Iraq invaded Iran. For the next eight years, a war of awful bloodshed raged at the head of the Persian Gulf, one that had even global repercussions by endangering oil supplies from the Middle East to Western Europe, North America and Japan.
It was a trial of strength between one country led by a dictator with a near Stalinist attachment to power and another country headed by a theocrat whose paranoid world view turned out to be a self-fulfilling prophecy.
In an age of simmering guerrilla conflicts (such as Vietnam and Nicaragua) and swift mobile campaigns (such as past Arab-Israeli clashes and the Falklands War). The Iran Iraq clash was a throwback to a simpler, bloodier time. It was a clash in which Iran's massive forces tried to overwhelm strong Iraqi linear defences, and in which Iraq coped with Iranian breakthroughs with the sort of mobile counterattacks pioneered by the Germans in Soviet Russia during World War II.
Despite the prodigious use of modern weaponry, it was-in the end--a very pre-modern war.