It was replaced by a static war, characterised by fixed defences, trench lines, bunkers, patrols, wiring parties and minefields reminiscent of the Western Front in 1915–17.

[3] Shortly after the Battle of Heartbreak Ridge got under way in September 1951, US Eighth Army commander General James Van Fleet and his staff drew up plans for an ambitious advance in the US I and IX Corps sectors.

Besides improving communications in central Korea, Van Fleet intended to use the railroad to support a follow-up operation in October which he had named Wrangle.

Van Fleet frankly recognized that this operation would be a calculated risk and might lead to a dangerous PVA/KPA counterthrust on the west flank as the amphibious forces tried to link up with the US IX Corps along the Kumsong-Kojo road.

[4] Although Van Fleet asked UN commander General Matthew Ridgway for a quick decision on Cudgel and Wrangle, he discarded them himself within a few days.

Consideration of the probable costs of Cudgel led him to accept instead a substitute plan submitted by General John W. O'Daniel, the I Corps' commander, at the end of September.

On the Corps' western flank the ROK 1st Infantry Division, commanded by Brigadier general Bak Lim Hang, would leave Line Wyoming, cross the Imjin River, and move toward Kaesong.

The British Commonwealth Division, under General James Cassels, was on the eastern flank of the ROK 1st and would take the high ground between Samich'on and Kyeho-dong.

Still farther east, the 1st Cavalry Division, under Major general Thomas Harrold, would move to the northwest on an 8 miles (13 km) front between Kyeho-dong and Kamgol.

Elements of the PVA 139th and 141st Divisions of the 47th Army manned the PVA's main line of resistance facing the 1st Cavalry Division and they had constructed defenses similar to those encountered on Heartbreak Ridge, strong bunkers supporting each other with automatic weapons fire, and with heavy concentrations of artillery and mortars interdicting the approach routes to the hills and ridges.

[4]: 99 Harrold had the 70th Tank Battalion under Major Carroll McFalls, Jr. and the 16th Reconnaissance Company operate as a task force on his left flank.

The mission of Task Force Mac was to advance along the east bank of the Imjin River toward Kyeho-dong, tying in with the 1st Commonwealth Division's move to the west and protecting the left flank of the 5th Cavalry Regiment.

Task Force Mac on the left flank encountered heavy mine concentrations coupled with strong artillery and mortar fire; by the end of the day, it had made little progress.

Attacking with the 3rd, Greek and 2nd Battalions abreast, they attempted to storm Hills 418 and 313 along with the ridge and high ground extending from these points.

Many positions changed hands three or four times during the course of the day as bitter hand-to-hand fighting marked the intensity of the PVA resistance.

Prisoners of war taken on 5–6 October indicated that the PVA were falling back on new prepared defense lines 5–7,000 yards (4.6–6,400.8 m) to the northwest and that many units had been decimated in the opening days of the offensive; food and ammunition stocks, they also reported, were becoming exhausted.

The fall of Hill 347 meant that the 1st Cavalry now dominated the high ground comprising the Jamestown Line in the northeastern half of the divisional sector.

[4]: 101 The breach in the northeast had little immediate effect upon the PVA defense of the hills across the 5th Cavalry front, however, and the relentless hammering of artillery, mortar, and tank fire against the formidable bunker system failed to produce a breakthrough.