User:Jim101/Battle of Unsan

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The Battle of Unsan, also known as the Battle of Yunshan, was a series of engagments of the Korean War that took place on from October 25 to November 4, 1950 near Unsan in present-day North Korea. As part of the Chinese First Phase Campaign, the Chinese made repeated attacks against the Republic of Korea 1st Infantry Division near Unsan since October 25. In one of the first engagements between Chinese and US forces during the Korean War, the Chinese 39th Corps mistakenly attacked the unprepared US 8th Cavalry Regiment in Unsan on November 1, resulting in what has been called "one of the most devastating US losses of the Korean War."

Background
By October 1950, the United Nations (UN) forces had successfully broken out of the Pusan Perimeter in the extreme south of Korea and began an aggressive northward advance towards the China-Korea border. With the destruction of the Korean People's Army (KPA), the 1st Cavalry Division entered Pyongyang on October 19 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 (ROK) 1st Infantry Division to secure the Sup’ung Dam on the Yalu River by advancing through the town of Unsan.

Alarmed by the rapid collapse of the KPA, Mao Zedong ordered the People's Liberation Army's 13th Army to be reorganized into the People's Volunteer Army (PVA) for the upcoming intervention in Korea. Despite Mao's determination to intervene in Korea, Chinese military leadership expressed doubts on the ablity of the Chinese army to fight against the modern 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 October 15.

Locations and terrain
Unsan is a town in northwest Korea, and it is located fifty air miles from the Ch'ongch'on River mouth on the Korean west coast. Due to 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 juction 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 General Milburn's instruction, the ROK 1st Division advanced north on October 24 with the ROK 6th Infantry Division on its right and the US 25th Infantry Division on its left, and by the morning of October 25 the ROK 1st Division had captured Unsan. But with the UN forces spread thin across Korea, a 15 mi gap between the US 25th Division and ROK 1st Division soon leave the Korean left flank unprotected.

Upon noticing the thinly held UN frontline, the Chinese decided to launch a pincer movement against the 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 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 Division at the east of Unsan. Finally, the PVA 39th Corps would destroy the ROK 1st Division by infiltrating the gap between US 25th Division and the ROK 1st Division on the west of Unsan. Undetected by UN intelligence, the 120th Division arrived at the blocking position on October 24, with its 360th Regiment heavy fortified the hills north of Unsan. To obsure troop movements and to prevent UN air raids, the Chinese also set several forest fires by the end of October.

Initial skirmish
On October 25 at 10:30 a.m., the ROK 1st Division attacked north with its 12th Regiment on the western bank of Samtan River while the 15th Regiment trying to reach the eastern bank. But when the 15th Regiment was about to cross the river, the PVA 120th Division intercepted Koreans with heavy artiliery fire. The South Koreans first believed the resistance to be the last remnants of the KPA, but the perception soon changed with the capture of the first Chinese prisoner in the Korean War. The Chinese prisoner revealed that there are 10,000 Chinese soldiers waiting at the north of Unsan.

Faced with the sudden apperance of the large Chinese forces, the 1st Division tried to establish defensive positions by capturing the hills around Unsan. The South Koreans soon find themselves in a seesaw battle with the PVA 360th Regiment during the night of October 25. On 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 Division. Aided by airdrops, the US 6th Medium Tank Battalion and the US 10th Anti-Aircraft Artillery Group attached to the ROK 1st Division reopened the road on October 27. Several more attempts to advance north by the Koreans made little progress, and the fightings stopped by October 28.

Despite the warnings given by Brigadier General Paik Sun Yup, commander of the ROK 1st Division, a general feeling of optimism about the outcome of the war prevented these from being taken seriously. With the fightings reached a stalemate at Unsan, General Walton Walker of the Eight Army ordered the 8th Cavalry Regiment of the US 1st Cavalry Division to resume offensives north by relieving the ROK 12th Regiment. By the time the US 8st Cavalry reached Unsan on October 29, the ROK 11th Regiment of the 1st Division was also pulling out of Unsan, with the Chinese destroyed the ROK 6th Division on the east of Unsan. Unsan had now became a northern salient in the UN line containing only the 8th Cavalry Regiment and the ROK 15th Regiment.

Chinese counterattack
Still believing that the ROK 1st Division was tied up at Unsan, PVA commander Peng Dehuai give the go ahead for the 39th Corps to destroy the the Unsan garrison on the morning of November 1. The Chinese plan called 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 the US 1st Battalion defending the north of Unsan by the Samtan River, while 2nd and 3rd Battalion defending the west of the Unsan by the Nammyon River. The lack of UN manpower, however, created a one mile gap between the 1st and 2nd Battalion. The ROK 15th Regiment, on the other hand, had dig 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, was intercepted by PVA 343th Regiment of the 115th Division at Bugle Hill. With the trap discovered, the Chinese immediately launched their attacks at 5 p.m. Aided with rocket artillery support,  the 117th Division attacked the ROK 15th Regiment in full force while four Chinese battalions from the 116th Division struck the gap between the US 1st and 2nd Battalion. By 11 p.m., the heavy fightings destroyed the ROK 15th Regiment while the US 1st and 2nd Battalion were running out of ammunation. As the UN forces buckling around Unsan, General Milburn finally ordered the garrison to withdraw after learning the destruction of the ROK 6th Division on the right flank.

But before the withdraw could be carried out, the PVA 347th Regiment of the 116th Division had already entered the town of Unsan through the gap between the American battalions. Soon afterwards, several road blocks poped up behind the US 1st and 2nd Battalion. With the attacks gaining momentum, the PVA 348th Regiment of the 116th Division attacked southward from Unsan, amushing the UN forces at the road junction by 2:30 a.m. With all the roads blocked, the US 1st and 2nd Battalion had to escape by infiltrating the Chinese lines in small groups, abandoning most of their vehicles and heavy weapons alone the way. The surviving US and ROK soldiers reached UN lines by November 2.

While the US 1st and 2nd Battalion was under heavy attacks, the 3rd Battalion was left alone for most of the night. But by 3 a.m., a company of Chinese commandos from the 115th Division managed to infiltrate the battalion command post by disguising as ROK soldiers. The following surprise attack set many vehicles on fire while causing numerous casualties amongst the cavalryman, most of whom were still sleeping. By the time the confusing fightings 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 343th Regiment at Bugle Hill, but after suffering 530 casualties, the 5th Cavalry was forced to withdraw under orders from Major General Hobart Gay, commander of the US 1st Cavalry Divison. The trapped 3rd Battalion endured days of constant attacks, and the surviving soldiers managed to broke out of the perimeter by November 4. 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 UN lines, intended to push the UN forces back to the Ch'ongch'on River. But logistic difficulties soon forced the Chinese to disengage on November 5, thus ending the Chinese First Phase Campaign. Besides the victory at Unsan, the Chinese First Phase Campaign also destroyed the ROK 6th Division and one regiment from the ROK 8th Division. The Chinese had also suffered 10,700 casualties by the end of the campaign.

The Chinese victory at Unsan is 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 evaluated in detail by Chinese commanders. On the other hand, despite the heavy losses suffered by the US Eighty Army at Unsan, the United Nations Command still reluctant to believe that China had entered the war. PVA commander Peng Dehuai incorporated the lessons from Unsan for the upcoming Second Phase Campaign while General Douglas MacArthur ignored the Unsan disaster and launched the Home-by-Christmas Offensive, resulting the decisive battles at the Ch'ongch'on River and the Chosin Reservoir.