Editing Battle of Chosin Reservoir (section)

===Location, terrain and weather===
Chosin Reservoir is a man-made lake located in the northeast of the Korean peninsula.{{sfn|Russ|1999|p=65}} The name Chosin is the Japanese pronunciation of the Korean place name [[Changjin]], and the name stuck due to the outdated Japanese maps used by UN forces.{{sfn|Tucker et al.|2000|p=108}} The battle's main focus was around the {{convert|78|mi|km|adj=mid|-long}} road that connects [[Hungnam]] and Chosin Reservoir,{{sfn|Appleman|1990|p=32}} which served as the only retreat route for the UN forces.{{sfn|Appleman|1990|p=29}} Through these roads, Yudami-ni and Sinhung-ni,{{efn|name=Sinhung-ni|The town of Sinhung-ni referred to in this article should not be confused with another identically named town located at south of Yudami-ni on the west side of Chosin Reservoir. See {{harvnb|Appleman|1990|pp=30, 32, 221, 376}}.}} located at the west and east side of the reservoir respectively, are connected at Hagaru-ri (now Changjin-ŭp) ({{Coord|40.3838|N|127.249|E|region:KP-08|display=inline}}). From there, the road passes through Koto-ri ({{Coord|40.284|N|127.3|E|region:KP-08|display=inline}}) and eventually leads to the port of Hungnam.{{sfn|Appleman|1990|pp=28–31}} The area around the Chosin Reservoir was sparsely populated.{{sfn|Appleman|1990|p=25}}

The battle was fought over some of the roughest terrain during some of the harshest winter weather conditions of the Korean War.{{sfn|Appleman|1990|p=24}} The road was created by cutting through the hilly terrain of Korea, with steep climbs and drops. Dominant peaks, such as the Funchilin Pass and the Toktong Pass ({{Coord|40.3938|N|127.161|E|region:KP-08|display=inline}}), overlook the entire length of the road. The road's quality was poor, and in some places it was reduced to a one-lane gravel trail.{{sfn|Appleman|1990|pp=28–31}} On 14 November 1950, a cold front from [[Siberia]] descended over the Chosin Reservoir, and the temperature plunged, according to estimates, to as low as {{convert|-36|°F|°C}}.{{sfn|Appleman|1990|p=xi}} The cold weather created considerable danger of [[frostbite]] casualties and was accompanied by frozen ground, icy roads, and weapon malfunctions. Medical supplies froze; morphine syrettes had to be defrosted in a medic's mouth before they could be injected; blood plasma was frozen and useless on the battlefield. Even cutting off clothing to deal with a wound risked gangrene and frostbite. Batteries used for the Jeeps and radios did not function properly in the temperature and quickly ran down.{{sfn|Duncan|2013|p=190}} The lubrication in the guns gelled and rendered them useless in battle. Likewise, the springs on the firing pins would not strike hard enough to fire the round, or would jam.{{sfn|Tilstra|2014|p=192}}