Editing Battle of Chosin Reservoir (section)

===Breakout===
[[File:Chosin-Retreat.png|thumb|alt=A map showing the withdrawal of a military force south along a river|A map of the Retreat from the Changjin (Chosin) Reservoir]]
After a short rest, the breakout began on 6 December, with the 7th Marines as the vanguard of the retreating column, while the 5th Marines covered the rear.{{sfn|Appleman|1990|p=247}} At the same time, the much-delayed PVA 26th Army arrived at Hagaru-ri with its [[76th Division (People's Republic of China)|76th]] and [[77th Division (People's Republic of China)|77th Divisions]] to relieve the 58th and 60th Divisions.{{sfn|Roe|2000|p=379}} As the 7th Marines pushed aside the PVA 76th Division south of Hagaru-ri, the 5th Marines took over the Hagaru-ri perimeter and recaptured the East Hill from the 76th Division.{{sfn|Roe|2000|p=382}}{{sfn|Appleman|1990|p=260}} In a last effort to stop the breakout,{{sfn|Roe|2000|p=382}} the customary Chinese night attack was launched, with the 76th and 77th Division striking the Hagaru-ri perimeter from all directions.{{sfn|Guang|2007|p=97}} The Marines repulsed the attacks, inflicting heavy casualties.{{sfn|Appleman|1990|p=262}}

Meanwhile, the 7th Marines opened the road between Hagaru-ri and Koto-ri by capturing the high ground surrounding the road. But as soon as the Marines pulled out, the 77th Division returned to the peaks and attacked the column.{{sfn|Roe|2000|pp=382–383}}{{sfn|Appleman|1990|p=257}} Chaotic fighting broke out and the retreat was slowed to a crawl.{{sfn|Appleman|1990|pp=257–259}} The Marine night fighters returned to subdue the Chinese forces,{{sfn|Appleman|1990|p=257}} and most of the blocking troops were eliminated.{{sfn|Roe|2000|p=383}} On 7 December, the rest of the column managed to reach Kot'o-ri with little difficulty, with the last elements reaching Kot'o-ri that night.{{sfn|Alexander|1986|p= 361}}

After the failure of the 26th Corps at Hagaru-ri, the PVA High Command ordered the 26th and 27th Corps to chase the escaping UN force, with the 20th Corps assigned to block the escape route.{{sfn|Roe|2000|p=383}}{{sfn|Guang|2007|p=103}} But with most of the 20th Corps destroyed at Yudam-ni and Hagaru-ri, the only forces between Kot'o-ri and Hungnam were the remnants of the 58th and 60th Divisions.{{sfn|Roe|2000|p=341}} In desperation, Song Shilun ordered these troops to dig in at Funchilin Pass, while blowing up the vital bridge ({{Coord|40.232|N|127.296|E|display=inline}}), hoping the terrain and obstacles would allow the 26th and 27th Corps to catch up with the retreating UN forces.{{sfn|Xue & Li Part Four|2000}}{{sfn|Roe|2000|p=341}} 

The PVA 180th Regiment that occupied Hill 1081 ({{Coord|40.233|N|127.326|E|display=inline}}) blew up the original concrete bridge and two improvised replacements in succession, believing the bridge was rendered irreparable.{{sfn|Mossman|1990|p=137}}{{sfn|Appleman|1990|pp=288–296}} In response, the [[1st Battalion, 1st Marines]] (1/1) attacked Hill 1081 from the south, and the hill was captured on 9 December, though the defenders fought to the last man.{{sfn|Appleman|1990|pp=300–301}} At the same time, the 7th Marines and RCT-31 attacked the bridge from the north, only to encounter defenders who were already frozen in their [[Defensive fighting position|foxholes]].{{sfn|Alexander|1986|p= 364}}

[[File:Aerial view of the Changjin (Chosin) Reservoir penstocks in the Funchilin Pass, with a close-up of the damaged bridge.jpg|thumb|An aerial view of the Funchilin Pass, with a close-up of the blown bridge]]
With the path to Hungnam blocked at Funchilin Pass, eight [[C-119 Flying Boxcar]]s flown by the US [[314th Troop Carrier Wing]] were used to drop [[Bailey bridge|portable bridge sections]] by parachute.{{sfn|Appleman|1990|p=297}}{{sfn|Rumley|2010}} The bridge, consisting of eight separate {{convert|18|ft|m|abbr=on}} long, {{convert|2900|lb|kg|abbr=on}} sections, was dropped one section at a time, using a {{convert|48|ft|m|abbr=on}} parachute on each section.{{sfn|Appleman|1990|p=296}} Four of these sections, together with additional wooden extensions were successfully reassembled into a replacement bridge by Marine Corps combat engineers and the US Army 58th Engineer Treadway Bridge Company on 9 December, enabling UN forces to proceed.{{sfn|Appleman|1990|pp=296–304}} Outmaneuvered, the PVA 58th and 60th Divisions still tried to slow the UN advance with ambushes and raids, but after weeks of non-stop fighting, the two Chinese divisions combined had only 200 soldiers left.{{sfn|Guang|2007|p=108}} The last UN forces left Funchilin Pass by 11 December.{{sfn|Appleman|1990|p=314}}

One of the last engagements during the withdrawal was an ambush at Sudong ({{Coord|40.17|N|127.324|E|display=inline}}) by the pursuing PVA 89th Division,{{sfn|Guang|2007|p=108}} which Task Force Dog of the 3rd Infantry Division repulsed with little difficulty.{{sfn|Appleman|1990|pp=307–310}} The trapped UN forces finally reached the Hungnam perimeter by 21:00 on 11 December.{{sfn|Appleman|1990|p=316}}