User:Jim101/Battle of Onjong

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The Battle of Onjong, also known as the Battle of Wenjing, was a series of battles of the Korean War that took place from October 25 to October 29, 1950 around Onjong in present-day North Korea. As the main focus of the Chinese First Phase Campaign, the Chinese 40th Corps conducted a series of ambush against the Republic of Korea II Corps, effectively destroying the right flank of the US Eighth Army while stopping the UN advances towards the Yalu River.

Background
By October 1950, the the Korean People's Army (KPA) was effectively destroyed by the United Nations (UN) forces after the landing at Inchon. Despite the strong objections from the People's Republic of China, the US Eighth Army continued to advance into North Korea and towards the Sino-Korean border. As part of the Thanksgiving Offensive to end the war, Major General Yu Yae Hung ordered the Republic of Korea (ROK) II Corps launched an attack towards the Yalu River through the village of Onjong on October 23, 1950.

In response to the UN advances, Mao Zedong ordered the People's Liberation Army's North East Frontier Force to enter the conflict under the name People's Volunteer Army (PVA). In order to stabilize the rapidly collapsing Korean front, Mao authorized the First Phase Campaign, a bridgehead building operation with the aim of destroying the ROK II Corps, the vanguard and the right flank of the US Eighth Army. Under strict secrecy, the PVA entered Korea on October 15.

Locations and terrain
Onjong is a crossroad village located at the lower Ch'ongch'on River Vally, 10 mi northeast of Unsan. To the south, Onjong is connected to Huich'on, the staging area of the ROK II Corps for the Thanksgiving Offensive. To the north, Onjong is linked to the town of Kojang, which is located at 50 mi away from the Yalu River. Because of the hilly terrain at the Sino-Korean Border, Onjong is one of the few access points into the Yalu River area. The terrain also limits troop movements while providing ideal positions for ambushes.

Forces and strategy
Under orders from General Yu Yae Hung, the ROK 6th Infantry Division of the ROK II Corps advanced northward from Huich'on on October 24, and Onjong was captured on the same day. From Onjong, the ROK 7th Infantry Regiment of the 6th Division turned north and advanced towards Kojang, while the ROK 2nd Infantry Regiment planned to advance northwest from Onjong toward Pukchin. Because the UN Command expected no opposition from the destroyed KPA, the advances were not coordinated between the UN units. As the result, the ROK 7th Regiment managed to wonder into Chinese territories without much opposition, completely oblivious to the new threats surrounding them.

While the Koreans were advancing towards the Yalu River, the Chinese were also trying to deploy their units for the upcoming First Phase Campaign. As the PVA commander Peng Dehuai scrambling to setup his new command post at Taeyudong, the planned advance by the ROK 2nd Regiment threatened to overran his position. Without any KPA units near by to hide the presence of the Chinese, Peng Dehuai was forced to start the First Phase Campaign early by moving the PVA 40th Corps to intercept the ROK 2nd Regiment near Onjong. On the night of October 24, the 118th Division of the 40th Corps arrived at the blocking position, and the Chinese had set up numerous ambush positions on the ridges overlooking the Onjong-Pukchin road.

Initial contacts
On the morning of October 25 and with its 3rd Battalion on point, the 2nd Regiment started northwest from Onjong toward Pukchin, but the Koreans came under fire at 8 mi to the west of Onjong. The 3rd Battalion dismounted from their vehicles to disperse what they thought to be a small force of KPA, but the two Chinese regiments on the high grounds poured heavy fire onto the Korean left, front and right. The 3rd Battalion broke instantly, abandoning most of their vehicles and artillery along the way. About 400 survivors managed to escape the trap and fall back into Onjong.

When the ROK 2nd Regiment learned that the 3rd Battalion was under heavy attack, the ROK 2nd Battalion was moved forward to support the 3rd Battalion while the ROK 1st Battalion was sent back to Onjong. While advancing, the ROK 2nd Battalion captured some prisoners, who revealed that there were nearly 10,000 Chinese soldiers waiting down the road. At the same time. the PVA High Command ordered the PVA 120th Division of the 40th Corps to join the battle while the 40th Corps was busy setting up roadblocks around Onjong. With all the roadblocks setup by midnight, the PVA 118th Division and one regiment from the PVA 120th Division attacked Onjong on October 26 at 3:30 a.m., and the ROK 2nd Regiment was dispersed within 30 minutes. Colonel Ham Byung Sun, commander of the 2nd Regiment, managed to rally his troops at 5 km east of Onjong, but the Chinese still managed to penetrate his position within an hour. At this point not a single company of the regiment was left intact, and the 2nd Regiment ceased to be an organized unit. Approximately 2,700 men of the 3,100 in the regiment eventually escaped to the Ch'ongch'on River. 3rd Battalion's Korean Military Advisory Group (KMAG) adviser, Lieutenant Glen C. Jones, was among those captured, and he eventually died in a North Korean prison camp. Captain Paul V. S. Liles of the KMAG also fell captive to the Chinese.

Second ambush
For Mao, the loss of surprise due the the early start of the First Phase Campaign greatly disappointed him. Nevertheless, Mao still urged Peng to destroy the South Koreans by baiting with trapped ROK units. At the same time, Major General Yoo Jai Hung, commander of the ROK II Corps, sent the ROK 19th Infantry Regiment of the 6th Division and the ROK 10th Infantry Regiment of the 8th Infantry Division to recapture Onjong and to salvage lost equipments. The ROK 7th Regiment was also ordered to retreat south by the 6th Division. Hoping to draw the the rest of the ROK II Corps into the open, Peng ordered the PVA 118th Division to swing north and trap the retreating ROK 7th Regiment, while the PVA 119th and the 120th Division of the 40th Corps would wait for any rescue forces passing through Onjong. On October 27, the PVA 118th Division quickly isolated ROK 7th Regiment by cutting the road between Kojang and Onjong, but the ROK 7th Regiment's did not reach the roadblock due to lack of supply. Upon realizing that the ROK II Corps did not take the bait, Peng ordered the 119th and the 120th Division to destroy the ROK 19th Regiment and the ROK 10th Regiment at Onjong. On the night of October 28, the Chinese divisions quickly desolated the two ROK regiments at the east of Onjong, and the Chinese roadblocks in the rear areas forced the Koreans to abandon all vehicles and artillery in order to escape.

By October 29, the ROK 7th Regiment was the only surviving formation of the ROK 6th Division, but it too was ambushed by the PVA 118th Division on October 29 at 20 mi south of Kojang. The PVA 118th Division was ordered to wait for reinforcements from the 50 Corps before attacking the ROK 7th Regiment, but the 118th Division attacked alone on the night of October 29 to prevent the Koreans from escaping. After a two hours long battle, the ROK 7th Regiment was ordered to disperse with its survivors scattered into the hills. About 875 officers and 3,552 soldiers managed to escape, while Major Harry Fleming of the KMAG was wounded in fifteen places and was later captured by the Chinese.

Aftermath
With the loss of the ROK 6th Division and the ROK 10th Regiment from the 8th Division, the ROK II Corps was effectively ceased to be an organized fighting organization, thus leaving the right flank of the US Eighth Army completely open to the Chinese. Exploiting the situation, the Chinese launched another attack towards the now exposed Eighth Army center, resulting in the loss of the ROK 15th Infantry Regiment and the US 8th Cavalry Regiment at the Battle of Unsan. With the Chinese forces advancing rapidly towards the rear of the UN lines, the Eighth Army was forced to retreat to the Ch'ongch'on River. Only the stubborn defense at Kunu-ri by the US 5th Regimental Combat Team and the ROK 7th Infantry Division managed to prevent a disastrous defeat for the Eighth Army. By November 5, logistics difficulties forced the Chinese to end the First Phase Campaign against the Eighth Army.

Although the Chinese was unable to exploit this major breakthrough, the weakness of the ROK II Corps on the Eighth Army right flank was exposed to Chinese commanders. During the planning of the Chinese Second Phase Campaign, Peng would again focus his attention towards the ROK II Corps at the Eighth Army's right flank, resulting in the disastrous defeat for the UN forces at the Battle of Ch'ongch'on River.