The Battle of Unsan , also known as the Battle of Yunshan , was a series of engagements of
the Korean War that took place from 25 October to 4 November 1950 near Unsan, North Pyongan
province in present-day North Korea. As part of the Chinese First Phase Campaign, the People's
Republic of China's People's Volunteer Army made repeated attacks against the Republic
of Korea 1st Infantry Division near Unsan beginning on 25 October, in an attempt to
take advancing United Nations forces by surprise. In an accidental first encounter with the
United States military during the Korean War, the Chinese 39th Corps attacked the unprepared
US 8th Cavalry Regiment in Unsan on 1 November, resulting in one of the most devastating US
losses of the Korean War. Background
By October 1950, the United Nations forces had successfully broken out of the Pusan Perimeter
in the extreme south of Korea and begun an aggressive northward advance towards the Sino-Korean
border, chasing the now defeated army of North Korea. With the destruction of the Korean
People's Army , the US 1st Cavalry Division entered Pyongyang on 19 October, while the
South Korean troops were rushing towards the Yalu River in all directions. As part of the
Thanksgiving Offensive to end the war, Major General Frank W. Milburn, commander of the
US I Corps, ordered the Republic of Korea 1st Infantry Division to secure the Sup'ung
Dam on the Yalu River by advancing through Unsan.
Alarmed by the rapid collapse of the KPA, China's Chairman Mao Zedong ordered the People's
Liberation Army's North East Frontier Force to be reorganized into the People's Volunteer
Army for the upcoming intervention in Korea. Despite Mao's determination to save North
Korea from capitulation, the Chinese military leadership expressed doubts on the ability
of the Chinese army to fight against the more modernized US forces. As a compromise, Mao
authorized the First Phase Campaign, a bridgehead building operation with limited offensives
against only the South Korean forces while avoiding contacts with the US forces. Under
strict secrecy, the PVA entered Korea on 19 October.
Prelude Locations and terrain
Unsan is a town in northwest Korea, and it is located 50 mi from the Ch'ongch'on River
mouth on the Korean west coast. Because of the hilly terrains at the Sino-Korean Border,
Unsan is one of the few access points into the Yalu River area. The town is surrounded
by hills to the north, the Nammyon River to the west and the Samtan River to the east.
At the south of the town, a road junction controls the road from Unsan to Ipsok while
a ridge dubbed "Bugle Hill" controls the road between Unsan and Yongsan-dong. Those two
roads formed the only retreat routes for the UN forces at Unsan.
Forces and strategy Acting on Milburn's instruction, the ROK 1st
Infantry Division advanced north on 24 October with the ROK 6th Infantry Division on its
right and the US 24th Infantry Division on its left, and by the morning of 25 October,
the ROK 1st Infantry Division had captured Unsan. But with the UN forces spread thin
across Korea, a 15 mi gap was left between the US 24th Division and ROK 1st Division,
leaving the Korean left flank unprotected.
Upon noticing the thinly held UN frontline, the Chinese decided to launch a pincer movement
against the South Koreans at Unsan. As part of the First Phase Campaign, the PVA 120th
Division of the 40th Corps was at first to block and hold the ROK 1st Infantry Division
at Unsan. Simultaneously, the bulk of the 40th Corps, together with the PVA 38th Corps
and one division from the 42nd Corps, would attack and destroy the ROK 6th and 8th Infantry
Divisions at the east of Unsan. Finally, the PVA 39th Corps would destroy the ROK 1st Infantry
Division by infiltrating the gap between US 24th Division and the ROK 1st Infantry Division
west of Unsan. Undetected by UN intelligence, the 120th Division arrived at the blocking
position on 24 October, with its 360th Regiment heavily fortified the hills north of Unsan.
To obscure troop movements and to prevent UN air raids, the Chinese also started several
forest fires around the end of October.
Battle Initial skirmish
On 25 October at 10:30, the ROK 1st Infantry Division attacked north with its 12th Regiment
on the western bank of Samtan River while the 15th Regiment was trying to reach the
eastern bank. But when the 15th Regiment was about to cross the river, the PVA 120th Division
intercepted the South Koreans with heavy artillery fire. The South Koreans first believed the
resistance to be the last remnants of the North Korean People's Army, but the perception
soon changed with the capture of the first Chinese prisoner in the Korean War. The prisoner
revealed that there were 10,000 Chinese soldiers waiting to join the fight north of Unsan.
Faced with the sudden appearance of the overwhelming Chinese forces, the ROK 1st Infantry Division
tried to establish defensive positions by capturing the hills around Unsan. The South
Koreans soon found themselves in a seesaw battle with the PVA 360th Regiment during
the night of 25 October. The next day, the PVA 39th Corps arrived at the west of Unsan
while cutting the road between Unsan and Yongsan-dong, completely surrounding the ROK 1st Infantry
Division. Aided by airdrops, the US 6th Medium Tank Battalion and the US 10th Anti-Aircraft
Artillery Group of the ROK 1st Infantry Division reopened the road on 27 October. Several more
attempts to advance north by the Koreans made little progress, and the fighting stopped
by 28 October.
Despite the warnings given by Brigadier General Paik Sun Yup, commander of the ROK 1st Infantry
Division, a general feeling of optimism about the outcome of the war prevented the warnings
from being taken seriously. With the fighting reached a stalemate at Unsan, General Walton
Walker of the Eighth United States Army ordered the US 8th Cavalry Regiment of the US 1st
Cavalry Division to resume offensives north by relieving the ROK 12th Regiment. By the
time the US 8th Cavalry Regiment reached Unsan on 29 October, the ROK 11th Infantry Regiment
of the ROK 1st Infantry Division was also pulling out of Unsan. At the same time, the
Chinese had destroyed the ROK 6th Infantry Division on the east of Unsan. Unsan had now
became a northern salient in the UN line containing only the US 8th Cavalry Regiment and the ROK
15th Infantry Regiment.
Chinese counterattack Still believing that the ROK 1st Infantry
Division was tied up at Unsan, PVA Commander Peng Dehuai gave the go ahead for the 39th
Corps to destroy the Unsan garrison on 1 November. The Chinese plan called for the PVA 117th
Division to attack from the northeast, the 116th Division to attack from the northwest
and the 115th Division to attack from the southwest. At the same time, the US 8th Cavalry
Regiment had taken up positions around the town, with its 1st Battalion defending the
north of Unsan by the Samtan River, while its 2nd and 3rd Battalions defending the areas
west of the Unsan by the Nammyon River. The lack of UN manpower, however, created a 1
mi gap between the 1st and 2nd Battalions. The ROK 15th Infantry Regiment, on the other
hand, had dug in northeast of the Unsan, across the river from the US 1st Battalion.
In the early afternoon of 1 November, a combat patrol from the US 5th Cavalry Regiment, rear
guard of the 8th Cavalry Regiment, was intercepted by PVA 343rd Regiment of the 115th Division
at Bugle Hill. With the trap discovered, the Chinese immediately launched their attacks
at 17:00. Aided with rocket artillery support, the 117th Division attacked the ROK 15th Infantry
Regiment in full force while four Chinese battalions from the 116th Division struck
the gap between the 1st and 2nd Battalions of the US 8th Cavalry Regiment. By 23:00,
the heavy fighting destroyed the ROK 15th Infantry Regiment while the US 1st and 2nd
Battalions were running out of ammunition. As the UN forces began to buckle around Unsan,
Milburn finally ordered the garrison to withdraw after learning the destruction of the ROK
6th Infantry Division on the right flank.
Before the withdrawal could be carried out, however, the PVA 347th Regiment of the 116th
Division had already entered the town of Unsan through the gap between the American battalions.
Soon afterward, several road blocks appeared behind the US 1st and 2nd Battalions. With
the attacks gaining momentum, the PVA 348th Regiment of the 116th Division advanced southward
from Unsan, ambushing the UN forces at the road junction by 02:30. With all the roads
blocked, the US 8th Cavalry Regiment's 1st and 2nd Battalions had to escape by infiltrating
the Chinese lines in small groups, abandoning most of their vehicles and heavy weapons along
the way. The surviving US and ROK soldiers reached UN line by 2 November.
While the US 8th Cavalry Regiment's 1st and 2nd Battalions were under heavy attack, its
3rd Battalion was left alone for most of the night. But by 03:00, a company of Chinese
commandos from the 116th Division managed to infiltrate the battalion command post disguised
as ROK soldiers. The following surprise attack set many vehicles on fire while causing numerous
casualties among the Americans, most of whom were still sleeping. By the time the confusing
fighting had ended, the 3rd Battalion was squeezed into a 200 yd wide perimeter by the
PVA 345th Regiment of the 115th Division. The US 5th Cavalry Regiment made repeated
attempts to rescue the 3rd Battalion by attacking the PVA 343rd Regiment at Bugle Hill, but
after suffering 350 casualties, the 5th Cavalry was forced to withdraw under orders from Major
General Hobart Gay, commander of the US 1st Cavalry Division. The trapped 3rd Battalion
endured days of constant attacks, and the surviving soldiers managed to break out of
the perimeter by 4 November. By the end of the battle, less than 200 survivors from the
3rd Battalion managed to return to the UN line.
Aftermath Immediately after the success at Unsan, the
rest of the Chinese forces advanced across the US lines, intending to push the US forces
back across the Ch'ongch'on River and into Pyongyang. But food and ammunition shortages
soon forced the Chinese to disengage on 5 November, thus ending the Chinese First Phase
Campaign. Besides the victory at Unsan, the Chinese First Phase Campaign also destroyed
the ROK 6th Infantry Division and one regiment from the ROK 8th Infantry Division at the
Battle of Onjong. In return, the Chinese had suffered 10,700 casualties by the end of the
Chinese First Phase Campaign. The Battle of Unsan has been considered to be one of the
most devastating US losses of the Korean War.
The Chinese victory at Unsan was as much of a surprise to the Chinese leadership as it
was to the UN forces. The accidental encounter between the Chinese and US forces at Unsan
eased the fear of the Chinese leadership about intervening in Korea, while the performance
of the US 1st Cavalry Division was studied in great detail by Chinese commanders. For
the UN forces, on the other hand, despite the heavy losses suffered by the US Eighth
Army at Unsan, the unexpected Chinese withdrawal made the United Nations Command believe that
China did not intervene in Korea on a large scale. PVA Commander Peng Dehuai incorporated
the lessons from Unsan for the upcoming Second Phase Campaign, while General Douglas MacArthur
launched the Home-by-Christmas Offensive under the assumption that only a weak Chinese force
was present in Korea, resulting in the decisive battles at the Ch'ongch'on River and the Chosin
Reservoir later that year.