The Gulf War oil spill is considered one of the biggest oil spills in history. During the beginning of the first war in Iraq, millions of gallons of oil were dumped into the Persian Gulf by the Iraqi military to thwart a potential landing by U.S. Marines. (By comparison, the Exxon Valdez spill was 10 million gallons, but estimates for this spill vary widely.)
On Jan. 21, 1991, two days after coalition forces launched their air assault on Iraq, Iraqi military forces opened the taps at an offshore oil terminal. The growing slick wasn't spotted for three days. A few days later, the U.S. Air Force bombed the terminal to try to stop the flow. The oil was blown south — half evaporated under the hot sun, a quarter of the remaining oil was recovered by Saudi Arabia with booms and skimmers, and the rest came to shore along 400 miles of Saudi and Kuwaiti beaches. Oil spilled for months and wasn't fully stopped until at least May.
In addition to the offshore taps, Iraqi soldiers also damaged and set alight hundreds of oil rigs on land; at the height of the action, more than 3 million barrels of oil was being burned a day, adding fuel to the oil spill. In addition to being possibly largest oil spill in history, it also was the most destructive example of environmental warfare in history.