Six US B-52 bombers have left RAF Fairford on their way back to airbases in America.
The bombers have flown more than 100 missions during the conflict
The huge planes have been stationed at the Gloucestershire site since the beginning of March.
After flying more than 100 sorties during the war on Iraq, the B-52s are expected to return to USAF bases in Minot, North Dakota, and Barksdale, Louisiana.
All 14 long-range bombers stationed at the base are expected to leave before the weekend.
The base was the focus of a number of large anti-war protests in the run-up to the conflict in the Gulf.
Activists who set up a peace camp near the perimeter fence were seen weeping as the bombers left to take part in their first raid on Iraq on 21 March.
Security around the site has been tight since the B-52s' arrival, with police invoking rarely used anti-terrorist stop-and-search powers and armed officers patrolling the area.
RAF Fairford is a NATO-designated forward base for US warplanes, and was also used by the bombers during the 1991 Gulf War and 1999 Kosovo conflict.
B-52s were designed to carry out nuclear attacks on the former Soviet Union, but gained fame for their deadly "carpet-bombing" runs during the Vietnam war.