Anbar campaign (2003–2011)

The Anbar campaign consisted of fighting between the United States military, together with Iraqi security forces, and Sunni insurgents in the western Iraqi governorate of Al Anbar. The Iraq War lasted from 2003 to 2011, but the majority of the fighting and counterinsurgency campaign in Anbar took place between April 2004 and September 2007. Although the fighting initially featured heavy urban warfare primarily between insurgents and U.S. Marines, insurgents in later years focused on ambushing the American and Iraqi security forces with improvised explosive devices (IEDs), large scale attacks on combat outposts, and car bombings. Almost 9,000 Iraqis and 1,335 Americans were killed in the campaign, many in the Euphrates River Valley and the Sunni Triangle around the cities of Fallujah and Ramadi.

Al Anbar, the only Sunni-dominated province in Iraq, saw little fighting in the initial invasion. Following the fall of Baghdad it was occupied by the U.S. Army's 82nd Airborne Division. Violence began on 28 April 2003 when 17 Iraqis were killed in Fallujah by U.S. soldiers during an anti-American demonstration. In early 2004 the U.S. Army relinquished command of the governorate to the Marines. By April 2004 the governorate was in full-scale revolt. Savage fighting occurred in both Fallujah and Ramadi by the end of 2004, including the Second Battle of Fallujah. Violence escalated throughout 2005 and 2006 as the two sides struggled to secure the Western Euphrates River Valley. During this time, Al Qaeda in Iraq (AQI) became the governorate's main Sunni insurgent group and turned the provincial capital of Ramadi into its stronghold. The Marine Corps issued an intelligence report in late 2006 declaring that the governorate would be lost without a significant additional commitment of troops.

In August 2006, several tribes located in Ramadi and led by Sheikh Abdul Sattar Abu Risha began to form what would eventually become the Anbar Awakening, which later led to the tribes revolting against AQI. The Anbar Awakening helped turn the tide against the insurgents through 2007. American and Iraqi tribal forces regained control of Ramadi in early 2007, as well as other cities such as Hīt, Haditha, and Rutbah. More hard fighting still followed throughout the Summer of 2007 however, particularly in the rural western River Valley, due largely to its proximity to the Syrian border and the vast network of natural entry points for foreign fighters to enter Iraq, via Syria. In June 2007 the U.S. turned a majority of its attention to eastern Anbar Governorate and secured the cities of Fallujah and Al-Karmah.

The fighting was mostly over by September 2007, although US forces maintained a stabilizing and advisory role through December 2011. Celebrating the victory, President George W. Bush flew to Anbar in September 2007 to congratulate Sheikh Sattar and other leading tribal figures. AQI assassinated Sattar days later. In September 2008, political control was transferred to Iraq. Military control was transferred in June 2009, following the withdrawal of American combat forces from the cities. The Marines were replaced by the US Army in January 2010. The Army withdrew its combat units by August 2010, leaving only advisory and support units. The last American forces left the governorate on 7 December 2011.