The Battle of Chosin Reservoir, also known as the Chosin Reservoir Campaign or the Changjin Lake Campaign (Korean: 장진호 전투(長津湖戰鬪); Chinese: 长津湖战役; pinyin: Cháng Jīn Hú Zhànyì), was a decisive battle in the Korean War. "Chosin" is the Japanese pronunciation of the Korean name, "Changjin". Reportedly, updated maps in Korean were unavailable, hence the use of maps reflecting the Japanese pronunciation (Korea had been liberated from Japanese colonial rule only five years prior, in 1945). Shortly after the People's Republic of China entered the conflict, the People's Volunteer Army 9th Army infiltrated the northeastern part of North Korea and surprised the US X Corps at the Chosin Reservoir area. A brutal 17 day battle in freezing weather soon followed. In the period between 27 November and 13 December 1950, 30,000 United Nations (UN) troops (nicknamed "The Chosin Few") under the command of Major General Edward Almond were encircled by approximately 67,000 Chinese troops under the command of Song Shi-Lun. Although Chinese troops managed to surround and outnumber the UN forces, they were able to break out of the encirclement while inflicting crippling losses on the Chinese, allowing them to successfully withdraw in good order. The evacuation of the X Corps from the port of Hungnam marked the complete withdrawal of UN troops from North Korea.