Operation (or Op) TELIC was the codename under which all British military operations in Iraq were conducted between the start of the Invasion of Iraq on 19 March 2003 and the withdrawal of the last remaining British forces on 22 May 2011. The bulk of the mission ended on 30 April 2009 but around 150 troops, mainly from the Royal Navy, remained in Iraq until 22 May 2011 as part of the Iraqi Training and Advisory Mission. 46,000 troops were deployed at the onset of the invasion and the total cost of war stood at £9.24 billion as of 2010

Operation Telic was one of the largest deployments of British forces since World War II. It was only approached in size by the 1991 Operation Granby deployment for the Gulf War and the 1956 Operation Musketeer Suez Crisis deployment. It was considerably larger than the 1982 Operation Corporate in the Falklands War, which saw around 30,000 personnel deployed and the Korean War, which saw fewer than 20,000 personnel deployed.

Some 9,500 of the British servicemen and women who deployed on Operation Telic for the invasion and its aftermath were reservists, the vast majority of them from the Territorial Army.