 Complete the following phrase:  In November 1950 when China surprised the United Nations ground troops with an unexpected counterattack from the Yalu River by the Peoples 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 