'The Gulf War' was originally the war between Iran
from 1980 to 1988. It cost the lives of at least 300,000 men, women and children, and left a million soldiers injured on both sides.
In 1980 Saddam Hussein started it by seeking to move his border into disputed Iranian territory, while his neighbour was reeling over the Islamic revolution and politically isolated from the West. However his invasion got bogged down outside Abadan in 1982; the Iranians counter-attacked and ended up bogged down outside Basra in 1987. Eventually the pair agreed to a UN brokered ceasefire.
During the latter part of the war came the underpublicised 'War of the Cities', when Iran and Iraq fired missiles at each other's cities. This was the first time in history that missiles were used in warfare against civilian targets by both sides. After patiently developing and stockpiling its own al-Hussein missiles, Iraq fired 189 Al-Hussein missiles at Tehran, Isfahan and Qom, killing 2,000 civilians over a two month period in 1988. Iran retaliated by launching 77 North Korean built Scud missiles against Iraqi cities, targetting mostly Baghdad. While the number of casualties on both sides per missile was actually not as high as the V2 missiles in World War Two (when one factors that London in 1944 had a much lower population density than Tehran in 1988), the attacks had the effect of causing widespread panic. A quarter of Tehran's population fled, and these attacks probably helped bring the war to a conclusion.
The term was subsequently appropriated and used for the considerably less bloody Desert Storm in 1991. And again in 2003, although some people call it 'Gulf War 2' (should it be Gulf War 3 ?). At any rate, these conflicts took place on land and not in the Persian Gulf.