The 3rd ACR departed Ramadi in September 2003, handing it over to the 1st Brigade Combat Team, 1st Infantry Division (1st BCT, 1st ID) of Fort Riley, Kansas; however, until March, the 1st BCT fell under the command of the 82nd Airborne Division.
During the first half of 2004, 1st BCT's two battalions (1-16th Infantry, 1-34th Armor) were augmented by the 2nd Battalion 4th Marines (2/4) and 3rd Battalion 11th Marines (3/11).