Direct proof of use
The 120 mm Royal Ordnance L11 appears in the 1990 Gulf War through British Challenger 1 tanks. Defense Advancement identifies Challenger 1's main armament as the rifled 120 mm L11A5 cannon and states that the tank deployed in Operation Granby, the British operation in the Gulf War.
The World Wars.net gives the same carrier link, listing Challenger 1's main armament as the L11A5 120 mm rifled gun and describing more than 100 Challenger 1 tanks deployed with the 1st (UK) Armoured Division in Operation Granby. Army Recognition also identifies the Challenger 1's armament as the 120 mm L11A5 rifled tank gun and states that Challenger 1 was deployed for British combat operations during the 1990-91 Gulf War.
Sources: Defense Advancement Challenger 1, The World Wars Challenger 1, Army Recognition Challenger 1
Timeline
In 1990, British Challenger 1 tanks deployed to the Gulf for Operation Granby as part of the coalition response to Iraq's invasion of Kuwait. Public technical summaries identify those tanks with the L11A5 120 mm rifled gun.
On 26 February 1991, British Challenger crews were in direct-fire action in Iraq. Captain Tim Purbrick's British Army Blog account describes Challenger main-gun engagements using FIN and HESH ammunition, including a T-55 engagement at about 3,600 m and a later target at about 4,700 m.
Sources: The World Wars Challenger 1, Army Recognition Challenger 1, British Army Desert Storm Part 22
Operational role
In Gulf War service, the L11A5 was not a separately deployed artillery piece; it was the Challenger 1 main gun. Its documented role was therefore the tank's direct-fire armament for armored combat, anti-armor fire, and fire support during the coalition ground offensive.
The available sources support British coalition use, not Iraqi use or independent transfer of the gun as a standalone weapon. The catalog side is recorded under the conflict's coalition-side ID because the canonical 1990 Gulf War conflict metadata groups coalition forces under a single side.
Sources: Defense Advancement Challenger 1, The World Wars Challenger 1, Army Recognition Challenger 1, British Army Desert Storm Part 22
