Direct proof of use
U.S. Army and DVIDS records directly document M109A6 Paladin use by U.S. forces during Operation Iraqi Freedom. At Camp Taji, Batteries A and B, 1st Battalion, 82nd Field Artillery Regiment fired thousands of rounds from M109A6 Paladin howitzers during Operation Iraqi Freedom Rotation 06-08, with more than 2,000 rounds described as combat missions supporting the 4th Stryker Brigade Combat Team, 2nd Infantry Division.
In northern Iraq, DVIDS documented Howitzer Battery, 3rd Armored Cavalry Regiment operating M109A6 Paladins at Badoush Prison outside Mosul in March and April 2008. The unit used the howitzers for nightly fire missions, mostly illumination rounds, in support of ground troops around Mosul.
Sources: Stryker Brigade Shows Appreciation for Dragon Fires, King of Battle Still Reigns in Modern Warfare, Paladin Howitzers Fire Rounds in Support of Ground Troops
Timeline
The available public record places M109A6 Paladin use across the occupation and counterinsurgency phase of the 2003 Iraq War rather than only in the initial March-April 2003 invasion. An Army historical study of 2003-2005 combat action describes a 155 mm round fired from an M109A6 Paladin during fighting around the Green Mosque near FOB Brassfield-Mora, while later Army and DVIDS reporting documents repeated Paladin fire missions from Camp Taji and Mosul.
By November 2007, the 1st Battalion, 82nd Field Artillery Regiment had fired more than 6,000 Paladin rounds during its Iraq rotation. In March and April 2008, Howitzer Battery, 3rd Armored Cavalry Regiment was documented conducting Paladin fire missions from Badoush Prison, including illumination support for ground troops.
Sources: Between the Rivers, Ironhorse Brigade Reflects on Progress, Stryker Brigade Shows Appreciation for Dragon Fires, King of Battle Still Reigns in Modern Warfare
Role in Iraq
The M109A6 Paladin appeared in Iraq as U.S. self-propelled 155 mm artillery for indirect fire support, counterfire, suppressive fires, pre-planned targets, and illumination. Camp Taji reporting tied the system to support for U.S. Stryker forces operating near Taji and Tarmiyah, while Mosul reporting described Paladins positioned at Badoush Prison to support ground movement and troops in contact.
The sources also show how the Paladin's role changed with the conflict environment. Army reporting from Taji in 2009 said artillery cannons in Iraq were often used as fixed pieces from stationary fire bases, but it also described Battery B, 1st Battalion, 82nd Field Artillery Regiment executing an on-the-move emergency fire mission with M109A6 Paladins in the Taji area.
Sources: Ironhorse Brigade Reflects on Progress, Stryker Brigade Shows Appreciation for Dragon Fires, King of Battle Still Reigns in Modern Warfare, Dragons Display Artillery Abilities