 In late @-@ September and early @-@ October — even while continuing the attack against Heartbreak Ridge — Van Fleet developed a plan for a limited offensive in the western section , known as Operation Commando , to advance 10 kilometres ( 6 @.@ 2 mi ) north of the 38th parallel , with the aim of pushing Chinese forces back and giving United Nations forces more leverage at the truce negotiations now occurring at <unk> . Operation Commando was scheduled for 3 – 5 October 1951 and the US I Corps commander , Lieutenant General John W. O <unk> , envisioned a concept of operations in which three of the corps ' four divisions would advance on a broad front in conjunction with US 25th Infantry Division on the left flank of the neighbouring US IX Corps , seizing a new defensive line known as the Jamestown Line . The divisions to be used in the advance included the 1st Commonwealth Division , US 1st Cavalry Division and the 9th South Korean Division . The 1st South Korean Division would remain in its existing position on the left flank . 
