Regiment, 7th Infantry Division …”. Liberation of Pusan Throughout October, as United Nations Forces crossed the 38th parallel to capture North Korea, the RCT-31 now commanded by Colonel Allan D. Maclean maneuvered 200 miles south over land toward Pusan (Busan); recapturing towns, liberating prisoners, and killing/capturing the remaining North Korean forces. When they reached Pusan, they were tasked with increasing combat effectiveness (training) with emphasis on physical conditioning, mountain warfare, communications and control, coordination of fire and control, and maintenance of equipment. When not training, they were confined to the USS General M. M. Patrick (AP-150) in Pusan harbor. United Nations offensive into North Korea On 25 October 1950, the People's Volunteer Army crossed the Yalu River into North Korea and attacked United Nations Forces at the Battle of Onjong. The 31st Regimental Combat Team was ordered to join the United Nations Forces in the “Home by Christmas Offensive”. They were to land 360 miles north at Riwŏn (Iwon) beach via another amphibious invasion called Operation Tailboard. Operation Tailboard RCT-31 landed on Riwŏn (Iwon) beach on 3 November 1950 at 2:00pm. They were tasked with guarding the left flank of the 17th Infantry Regiment in the mountains toward the Pujŏn-ho (Fusen) Reservoir while the 17th captured Kapsan. Fusen Reservoir RCT-31 reached the Pujŏn-ho (Fusen) Reservoir on 15 November 1950 and engaged with ~200 Chinese forces which were repulsed with air strikes via a Marine F4U Corsair. After securing the area, they conducted rotating patrols for the next week while enduring an early winter with temperatures reaching -2 °F. By November 23, 83 soldiers of RCT-31 were treated for frostbite with 33 evacuated. They also conducted a search and rescue operation that successfully located and retrieved a Marine pilot. Chosin Reservoir The 7th Infantry Division was ordered by Major General Ned Almond, X Corps commander, to provide a regiment-sized force to guard the Marines' east (right) flank, by occupying the east side of the reservoir. This force would also attack north to the Yalu River, the boundary between North Korea and China, once the offensive began. In earlier operations, 7th Division units had become widely spread out and isolated from each other in the rugged, mountainous terrain and primitive road network of the region. This made it impossible to assemble a full-strength task force in time, or to effectively coordinate its operations with the Marines on the south and western sides