Battle of Onjong

The Korean War began on 25 June 1950 when the North Korean Korean People's Army (KPA) attacked South Korea. The invasion was almost successful in conquering all of South Korea until the UN intervened, sending ground forces into the country under the command of the United States. The UN forces initially experienced early defeats until the Battle of the Pusan Perimeter, where the UN forces reversed the KPA's momentum. By October 1950, the KPA was effectively destroyed by the UN forces after the landing at Inchon, the breakout from the Pusan Perimeter and the UN September 1950 counteroffensive. Despite the strong objections from the People's Republic of China on North Korea's northern border, the US Eighth Army crossed the 38th Parallel and advanced towards the Sino-Korean border at the Yalu River. In order to stabilize the rapidly collapsing Korean front and to push back the advancing UN forces, 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, advancing up along the Taebaek Mountains in the middle of the peninsula. After the Chinese leadership finally settled the issue of armed intervention on October 18, Mao ordered the PVA to enter Korea on 19 October under strict secrecy. ==Prelude==

Locations and terrain Onjong is a crossroad village located at the lower Ch'ongch'on River Valley, northeast of Unsan. At the east of Onjong stands the town of Huich'on, the staging area of the ROK II Corps for the offensive. The terrain also limits troop movements while providing ideal grounds for ambushes. From Onjong, the ROK 7th Infantry Regiment, 6th Infantry Division turned north and advanced towards Kojang, While the ROK were advancing towards the Yalu River, the PVA were also trying to deploy their units for the upcoming First Phase Campaign. As the PVA Commander Peng Dehuai scrambled to set up his new command post at Taeyudong, the planned advance by the ROK 2nd Infantry Regiment threatened to overrun his position. Without any KPA units nearby to hide the presence of the PVA, Peng was forced to start the First Phase Campaign early by moving the PVA 40th Corps to intercept the ROK 2nd Infantry Regiment near Onjong. ==Battle==

Initial contacts On the morning of 25 October and with its 3rd Battalion on point, the ROK 2nd Infantry Regiment started to advance northwest towards Pukchin. The ROK soon came under fire to the west of Onjong. The 3rd Battalion broke instantly, abandoning most of its vehicles and artillery along the way. Although the 2nd Battalion was turned back after encountering strong resistances, the ROK managed to capture several Chinese prisoners who revealed that there were nearly 10,000 Chinese soldiers waiting down the road. At this point not a single company of the regiment was left intact, and the ROK 2nd Infantry Regiment ceased to be an organized unit. Two US Army Korean Military Advisory Group (KMAG) advisors were also captured. Nevertheless, Mao still urged Peng to destroy the ROK by baiting them with trapped units. At the same time, Major General Yu Jae-hung, commander of ROK II Corps, sent the ROK 19th Infantry Regiment, 6th Infantry Division (under Colonel Park Kwang Hyuk) and the ROK 10th Infantry Regiment, 8th Infantry Division (under Colonel Go Geun Hong) to recapture Onjong and to salvage the lost equipment from the battle. while the PVA 119th and 120th Divisions would wait to ambush any rescue forces passing through Onjong. but the ROK 7th Infantry Regiment did not reach the roadblock due to the lack of fuel. Upon realizing that ROK II Corps had not fallen for the deception, Peng ordered the 119th and the 120th Divisions to destroy the ROK 10th and 19th Infantry Regiments. The ROK 7th Infantry Regiment had now become the only surviving formation of the ROK 6th Infantry Division, but it too was ambushed by the PVA 118th Division on 29 October south of Kojang. About 875 officers and 3,552 other soldiers managed to escape, while Major Harry Fleming of the Korean Military Advisory Group was wounded fifteen times and was later captured by the PVA. ==Aftermath==

With the loss of the ROK 6th Infantry Division and the ROK 10th Infantry Regiment, ROK II Corps was devastated, and effectively ceased to be an organized fighting force. This meant the right flank of the US Eighth Army was completely open to the PVA, which were now advancing south to overwhelm the UN forces. Exploiting the situation, the PVA launched another attack on 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. Only the stubborn defense of Kunu-ri by the US 5th Regimental Combat Team and the ROK 7th Infantry Division on 4 November managed to stop the PVA advance and prevented a disastrous defeat for the Eighth Army. By 5 November logistics difficulties forced the PVA to end the First Phase Campaign. Although the PVA were unable to exploit the breakthrough in the UN lines, the weakness of ROK II Corps on the Eighth Army's right flank was exposed to the PVA commanders. During the planning of the PVA Second Phase Offensive, Peng would again focus his attention towards ROK II Corps at the Eighth Army's right flank, To commemorate this battle as China's official entry into the Korean War, 25 October is currently the War to Resist America and Aid Korea Memorial Day in China. ==Notes==