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.
Despite repeated warnings from American and South Korean officers and intelligence sources, the US forces were surprised and unprepared when they encountered well-equipped and well-trained Chinese forces.
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 0500. 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 1100, 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, General 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 afterwards, 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 0230. 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 0300, 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 (180 m) 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 530 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.
After the Battle of Unsan, the "Chinese Peoples' Volunteer Army," published a pamphlet entitled, "Primary Conclusions of Battle Experiences at Unsan." In it, the Chinese listed what they considered the strengths and weaknesses of the American forces, based on their experience with the 8th Cavalry Regiment. On the favorable side the pamphlet described in some detail the American method of making an attack and said:
“The coordinated action of mortars and tanks is an important factor.... Their firing instruments are highly powerful. ... Their artillery is very active.... Aircraft strafing and bombing of our transportation have become a great hazard to us . . . their transportation system is great. . . . Their infantry rate of fire is great and the long range of fire is still greater. “Not so favorable was the Chinese estimate of the American infantry. The pamphlet said that American soldiers when cut off from the rear
“. . . abandon all their heavy weapons, leaving them all over the place, and play opossum.... Their infantrymen are weak, afraid to die, and haven't the courage to attack or defend. They depend on their planes, tanks, and artillery. At the same time, they are afraid of our fire power. They will cringe when, if on the advance they hear firing. They are afraid to advance farther.... They specialize in day fighting. They are not familiar with night fighting or hand to hand combat.... If defeated, they have no orderly formation. Without the use of their mortars, they become completely lost. . . they become dazed and completely demoralized.... At Unsan they were surrounded for several days yet they did nothing. They are afraid when the rear is cut off. When transportation comes to a standstill, the infantry loses the will to fight. “
After analyzing the Americans' strength and weakness, the Chinese set forth certain principles for future operations:
“As a main objective, one of the units must fight its way rapidly around the enemy and cut off their rear.... Route of attack must avoid highways and flat terrain in order to keep tanks and artillery from hindering the attack operations.... Night warfare in mountainous terrain must have a definite plan and liaison between platoon commands. Small leading patrol groups attack and then sound the bugle. A large number will at that time follow in column.“The Chinese admitted they did not have an effective weapon against the American tank, but said that 20-pound TNT charges placed on the tracks or under the tank would disable it. Antitank sections consisted of four men carrying two 20-pound and two 5-pound charges.
The Chinese summed up their viewpoint on the first phase of their intervention:
“Our Army [38th] was the first expeditionary force ordered to hurry to the Ung-pong area of Unsan to relieve the North Korean Army and intercept the enemy advancing northwards at Unsan. We deployed our main force to encircle and annihilate the enemy at Hichon [Huichon], Onjong, and Chosan. At that time, we did not fully comprehend the tactical characteristics and combat strength of the enemy, and we lacked experience in mountain warfare. Moreover, we engaged the enemy (first, in the form of interdiction, then in that of attack) without sufficient preparation; yet the result was satisfactory.”From the American perspective the result was not satisfactory.
One inspirational story that came from this battle was that of Corporal Tiber Ruben. He was a Holocaust survivor who came to the United States after the 2nd World War and made a vow to serve in the army that had freed him. In Korea he was part of the 8th Cavalry and was wounded and captured. The survival skills he learned in German camps kept him alive and he was credited with saving at least 40 other soldiers by risking his life sneaking out of the camp at night and stealing whatever food he could find then bringing it back to his companions. He was awarded the Congressional Medal of Honor for his heroism.