The Iran-Iraq War was a long and brutal conflict between the neighboring countries of Iran and Iraq.

It was started by Iraqi leader Saddam Hussein, who launched an invasion of Iran in September 1980.

Saddam's motivations included a desire to seize Iran's oil-rich Khuzestan province and to prevent the spread of Iran's Shia Islamic revolution to Iraq's own Shia majority.

The war quickly bogged down into a bloody stalemate with similarities to the trench warfare of World War I.

The conflict was characterized by immense casualties, human-wave attacks by Iran, and the use of chemical weapons by Iraq.

The 'War of the Cities' involved both sides launching missile attacks against each other's major urban centers.

The 'Tanker War' saw both Iran and Iraq attacking each other's oil tankers in the Persian Gulf.

During the war, most international powers, including the U.S. and the USSR, supported or tilted toward Iraq.

The war finally ended in 1988 with a UN-brokered ceasefire, with no significant territorial changes for either side.

It was one of the deadliest conventional wars of the 20th century, resulting in an estimated one million casualties.