Direct proof of use
The G5's Gulf War record is documented most directly through post-battle imagery. A Defense imagery file preserved on Wikimedia Commons identifies a South African-made G5 155 mm howitzer abandoned near the Arramaylan refinery by Iraqi forces during Operation Desert Storm, dated 3 March 1991 and credited to Staff Sgt. Dean Wagner.
PICRYL's U.S. National Archives-derived record for the same scene describes an abandoned Iraqi 155 mm G-5 towed howitzer surrounded by shells and casings near the Arramaylan refinery after an Allied attack. The photograph supports Iraqi fielding and abandonment of the weapon in the 1990 Gulf War; it does not by itself identify a specific firing mission or target.
Sources: Wikimedia Commons - Iraqi G5 howitzer in 1991, PICRYL - Abandoned Iraqi G-5 near Arramaylan
Narrative
In Iraqi service, the G5 belonged to the long-range tube-artillery layer that Iraq had built during the Iran-Iraq War and still held when it entered the Kuwait crisis. The weapon was a 155 mm, 45-caliber towed gun-howitzer with an auxiliary power unit for emplacement and short tactical movement; public technical references describe it as an indirect-fire weapon able to use extended-range full-bore ammunition.
The Gulf War evidence therefore shows possession and battlefield fielding by Iraqi forces rather than a detailed operational chronology. The abandoned Arramaylan refinery gun, photographed with shells and casings after an Allied attack, places an Iraqi G5 in the Operation Desert Storm battlespace and supports the compact catalog role of Iraqi heavy artillery and recovered or abandoned conflict materiel.
No reviewed source tied this specific G5 to a named Iraqi unit, a dated fire mission, or a quantified battlefield effect. Those details should remain unattributed unless a later official record, unit history, or well-identified battlefield account directly documents them.
Sources: Forecast International G5 155mm Howitzer, FAS G5 155mm Towed Gun-Howitzer, PICRYL - Abandoned Iraqi G-5 near Arramaylan