, also known as the Iraqi Imposed War (جنگ تحمیلی, Jang-e-tahmīlī), Holy Defense (دفاع مقدس, Defa-e-moghaddas) and Iranian Revolutionary War in Iran, and Saddām's Qādisiyyah (قادسيّة صدّام, Qādisiyyat Saddām) in Iraq, was a war between the armed forces of Iraq and Iran lasting from September 1980 to August 1988. It was commonly referred to as the Persian Gulf War until the Iraq-Kuwait conflict of (1990--91), and for a while thereafter as the First Persian Gulf War. The Iraq-Kuwait conflict, while originally known as the Second Persian Gulf War, later became known simply as the Persian Gulf War. Many have also considered it to be the Longest Conventional War of the 20th Century as there was a book written by historian Dilip Hiro with the same title, however this is strongly disputed among historians. It is also regarded in much of the West as one of the Forgotten Wars of the 20th Century. The war began when Iraq invaded Iran on 22 September 1980 following a long history of border disputes and demands for the overthrow of Saddam Hussein's regime. Although the Iraqis attacked without formal warning, they failed to make progress and were soon repelled by the Iranians. Despite several calls for a ceasefire by the United Nations Security Council, hostilities continued until 20 August 1988; the last prisoners of war were exchanged in 2003. The war altered regional and even global politics. The war is also noted for being very similar to World War I. Tactics such as trench warfare, manned machine-gun posts, bayonet charges, use of barb-wire, human wave attacks and Iraq's extensive use of chemical weapons (such as mustard gas) against Iranian troops and civilians as well as Iraqi Kurds.