By June 1951, 3 RAR moved to a position on the Imjin River under the command of the US I Corps and it was here that the battalion would spend the next two years of the war. The major action fought by the regiment in the second half of 1951 was the Battle of Maryang San, where 3 RAR, under the command of Lieutenant Colonel Frank Hassett, assaulted Hill 317 on 5 October 1951. Known as Operation Commando, Hill 317 was captured after five days of hard fighting. Following this action the war was defined by fixed defences of trenches, bunkers and wire, constant patrolling, and numerous clashes. In April 1952, 3 RAR was joined by 1 RAR and command of the 28th British Commonwealth Brigade, of which they were now a part, passed to an Australian officer as a result. Meanwhile, the expansion of the commitment in Korea to two battalions resulted in the establishment of a regimental depot at Ingleburn in 1952 to train and hold infantrymen for service in Korea. In April 1953, 1 RAR was replaced by 2 RAR on a system of unit rotation. During this changeover a parade was held to mark the first occasion that all battalions of the regiment had been on parade together. 1 RAR served a year in Korea, 2 RAR for four months before the armistice, while 3 RAR served throughout the war, earning itself the nickname of "Old Faithful". The last major action of the war for the regiment was the Battle of the Samichon River fought by 2 RAR over 24–26 July 1953, repulsing a number of major Chinese assaults just hours before the Armistice Agreement was signed.