In November 1950 when China surprised the United Nations ground troops with an unexpected counterattack from the Yalu River by the People's Liberation Army, "Philippine Sea" planes saw heavy action. The US Navy had sent "Valley Forge" and several other ships away from Korea, expecting the conflict to end, and so the unprepared forces remaining in the area were heavily engaged. Throughout the long retreat from the Yalu River, the four carriers' Panthers, Skyraiders and Corsairs provided close air support for the trapped X Corps at Chosin Reservoir. Though the increasingly cold weather proved a problem for "Philippine Sea", the ship continued to support the troops as they tried to evacuate from the reservoir and then cleared the path for their retreat to Hungnam. The carriers provided support with hundreds of aircraft sorties as 150,000 UN troops and civilians were evacuated, and then destroyed the port. During this support, "Valley Forge" and "Philippine Sea" were tightly clustered with and and commanders worried that they would be a target for air attack by North Korean MiG-15 fighters, prompting a large screen of 32 destroyers.For the rest of 1950 and early 1951, she launched numerous attacks against Chinese forces around the 38th Parallel hoping to slow their advance as UN troops retreated. With only brief stops for repair and rest, the carrier continued numerous sorties against Chinese targets. On 25 February, command of Task Force 77 was transferred to "Valley Forge". During this time, the cold weather hampered operations and blizzards occasionally shut them down completely. Putting into Yokosuka Naval Base, Japan, in late March 1951 for repair and refit, "Philippine Sea" exchanged Air Group 11 for Carrier Air Group 2 from "Valley Forge", a group which consisted mostly of Vought F4U Corsair fighter-bombers. The same date as the transfer on 28 March, "Philippine Sea" became flagship of Vice Admiral H. M. Martin, the commander of the 7th Fleet.