Editing Battle of Chosin Reservoir (section)

==Background==
{{See also|UN offensive into North Korea#1st Marine Division in the Chosin Reservoir (29 October – 25 November)}}
[[File:Race to Yalu Map.gif|thumb|left|alt=A map showing the Peninsula with US forces moving from the south to the north|A map of UN advances toward the [[Yalu River]]]]

By mid-October 1950, after the successful [[Battle of Inchon|landing at Inchon]] by the US [[X&nbsp;Corps (United States)|X&nbsp;Corps]], the Eighth Army [[Pusan Perimeter Offensive|breakout from the Pusan Perimeter]] and the subsequent [[UN September 1950 counteroffensive|pursuit and destruction]] of the [[Korean People's Army]] (KPA), the Korean War appeared to be all but over.{{sfn|Millett|2009}} [[United Nations Command (Korea)|United Nations]] (UN) forces [[UN offensive into North Korea|advanced rapidly]] into [[North Korea]] with the intention of reuniting North and South Korea before the end of 1950.{{sfn|Alexander|1986|p=312}} North Korea is divided through the center by the impassable [[Taebaek Mountains]], which separated the UN forces into two groups.{{sfn|Appleman|1990|p=3}} The US [[Eighth United States Army|Eighth Army]] advanced north through the western coast of the Korean Peninsula, while the Republic of Korea (ROK) [[I Corps (South Korea)|I Corps]] and the US X&nbsp;Corps advanced north on the eastern coast.{{sfn|Appleman|1990|p=3}}

At the same time the [[People's Republic of China]] entered the conflict after issuing several warnings to the United Nations.{{sfn|Roe|2000|pp=101–107}} On 19 October 1950, large formations of Chinese troops, dubbed the [[People's Volunteer Army]] (PVA), secretly crossed the border and into North Korea.{{sfn|Roe|2000|pp=145–149}} One of the first Chinese units to reach the Chosin Reservoir area was the PVA [[42nd Army (People's Republic of China)|42nd Army]], which was tasked with stopping the eastern UN advances.{{sfn|Guang|2007|p=46}} On 25 October, the advancing ROK I Corps made contact with the Chinese and halted at Funchilin Pass ({{Coord|40.204|N|127.3|E|display=inline}}), south of the Chosin Reservoir.{{sfn|Appleman|1990|p=5}} 

After the landing at [[Wonsan]], the US [[1st Marine Division (United States)|1st Marine Division]] of the X&nbsp;Corps engaged the defending PVA [[124th Division (People's Republic of China)|124th Division]] on 2 November; the ensuing battle caused heavy casualties among the Chinese.{{sfn|Appleman|1990|p=7}} On 6 November, the PVA 42nd Corps ordered a retreat to the north with the intention of luring the UN forces into the Chosin Reservoir.{{sfn|Guang|2007|p=47}} By 24 November, the 1st Marine Division occupied both [[Sinhung County|Sinhung-ni]]{{efn|name=Sinhung-ni}} ({{Coord|40.557|N|127.27|E|display=inline}}) on the eastern side of the reservoir and Yudami-ni ({{Coord|40.48|N|127.112|E|display=inline}}) on the west side.{{sfn|Appleman|1990|p=8}}

Faced with the sudden attacks by Chinese forces in the Eighth Army sector, General [[Douglas MacArthur]] ordered the Eighth Army to launch the [[Home-by-Christmas Offensive]].{{sfn|Appleman|1990|pp=24,33}} To support the offensive, MacArthur ordered the X&nbsp;Corps to attack west from the Chosin Reservoir and to cut the vital Manpojin—Kanggye—Huichon supply line.<ref>{{harvnb|Mossman|1990|p=48}}. {{PD-notice}}</ref>{{sfn|Appleman|1990|p=11}} In response, Major General [[Edward M. Almond]], commander of the US X&nbsp;Corps, formulated a plan on 21 November. It called for the US 1st Marine Division to advance west through Yudami-ni, while the US [[7th Infantry Division (United States)|7th Infantry Division]] would provide a [[regimental combat team]] to protect the right flank at Sinhung-ni. The US [[3rd Infantry Division (United States)|3rd Infantry Division]] would also protect the left flank, while providing security in the rear area.{{sfn|Appleman|1990|p=14}} By then the X&nbsp;Corps was stretched thin along a 400-mile front.{{sfn|Appleman|1990|p=8}}

Surprised by the Marine landing at Wonsan,{{sfn|Roe|1996}} [[Chinese Communist Party]] [[Chairman of the Communist Party of China|chairman]] [[Mao Zedong]] called for the immediate destruction of the ROK [[Capital Mechanized Infantry Division (Republic of Korea)|Capital Division]], ROK [[3rd Infantry Division (South Korea)|3rd Infantry Division]], US 1st Marine Division, and US 7th Infantry Division in a telegram to Commander{{efn|The Chinese military did not have [[military rank]]s during the 1950s.}} [[Song Shilun]] of the PVA 9th Corps on 31 October.{{sfn|Guang|2007|pp=47–48}} Under Mao's urgent orders, the 9th Corps was rushed into North Korea on 10 November.{{sfn|Appleman|1990|p=21}} Undetected by UN intelligence,{{sfn|Appleman|1990|p=35}} it entered the Chosin Reservoir area on 17 November, with the [[20th Army (People's Republic of China)|20th Army]] of the 9th Corps relieving the 42nd Army near Yudami-ni.{{sfn|Guang|2007|p=47}}