The Battle of Umm Qasr was the first military confrontation in the Iraq War. At the start of the war, one of the first objectives was the port of Umm Qasr. On March 21, 2003, as allied forces advanced across Southern Iraq, an amphibious landing force captured the new port area of Umm Qasr. The assault was spearheaded by Royal Marines of the British 3 Commando Brigade, augmented by Marines of the US 15th Marine Expeditionary Unit and Polish GROM troops. Iraqi forces in the old town of Umm Qasr put up unexpectedly strong resistance, requiring several days' fighting before the area was cleared of defenders. The port was finally declared safe and reopened on March 25, 2003.

After the waterway was de-mined by a detachment from HM-14 and Naval Special Clearance Team ONE of the U.S. Navy and reopened, Umm Qasr played an important role in the shipment of humanitarian supplies to Iraqi civilians.

Coalition minesweepers, including HMS Bangor, aided by divers, US Navy MH-53E helicopters, trained dolphins and seals, located the approach to the port and cleared it of mines, allowing RFA Sir Galahad to dock after a couple of days.

Umm Qasr (Arabic: أم قصر‎, also transliterated as : Um-qasir, Um-qasser), is a port city in southern Iraq. It stands on the canalised Khawr az-Zubayr, part of the Khawr Abd Allah estuary which leads to the Persian Gulf. It is separated from the border of Kuwait by a small inlet. A bridge across the waterway linked the port with Kuwait prior to the 1991 Persian Gulf War.

Umm Qasr was originally a small fishing town, but was used as a military port on several occasions before advancing trades and jobs by building a deep-water port on the coast. It was said to have been the site of Alexander the Great's landing in Mesopotamia in 325 BC. During the Second World War a temporary port was established there by the Allies to unload supplies to dispatch to the Soviet Union. It fell back into obscurity after the war, but the government of King Faisal II sought to establish a permanent port there in the 1950s.

After the Iraqi Revolution of 1958, a naval base was established at Umm Qasr. The port was subsequently founded in 1961 by the Iraqi ruler General Abdul-Karim Qassem. It was intended to serve as Iraq's only "deep water" port, reducing the country's dependence on the disputed Shatt al-Arab waterway that marks the border with Iran. The port facilities were built by a consortium of companies from West Germany, Sweden and Lebanon, with a railway line connecting it to Basra and Baghdad. The port opened for business in July 1967.