UN forces invaded Attack North Korea in October 1950 and moved Motion rapidly towards the Yalu River—the border with China—but on 19 October 1950 , Chinese forces of the People 's Volunteer Army ( PVA ) crossed Motion_directional the Yalu and entered Arriving the war Hostile_encounter .

The Battle Hostile_encounter of Pakchon ( 5 November 1950 ) , also known as the Battle Hostile_encounter of Bochuan ( ) , took place Process_start ten days after the start Process_start of the Chinese First Phase Offensive , following the entry Process_start of the Chinese People 's Volunteer Army ( PVA ) into the Korean War .

The battle Hostile_encounter was fought Hostile_encounter between British and Australian forces from the 27th British Commonwealth Brigade with American armour and artillery in support Supporting , and the PVA 117th Division of the 39th Army , around the village of Pakchon on the Taeryong River .

Meanwhile , immediately following their success Achieve at Unsan against the Americans , the PVA 117th Division had attacked Attack southward , intending to cut off Hindering the UN forces as they withdrew Escaping in the face of the unexpected PVA assault .

Meanwhile , immediately following their success Achieve at Unsan against the Americans , the PVA 117th Division had attacked Attack southward , intending to cut off Hindering the UN forces as they withdrew Escaping in the face of the unexpected PVA assault .

To halt Preventing_or_letting the PVA advance , the 27th British Commonwealth Brigade was ordered Arranging to defend Defending the lower crossings of the Taeryong and Chongchon rivers as part of a rearguard , in conjunction with the US 24th Infantry Division further upstream on the right .

During the night of 4/5 November , the PVA and Korean People 's Army ( KPA ) mounted a full-scale assault on the US 24th Infantry Division , pushing Motion back an American infantry regiment nearly .

The British and Australians then successfully counter-attacked Attack the PVA forces Causation occupying a number of nearby ridgelines during the day but were in turn counter-attacked Attack before being pushed Motion off the high ground during the night .

In their first battle Hostile_encounter with the PVA , the 3rd Battalion , Royal Australian Regiment ( 3 RAR ) captured Conquering a well defended Defending hill with only limited Limiting offensive support , and held Defending it in the face of heavy counter-attacks before confused Perception_active command Control decisions Deciding resulted in Causation a disorganised night withdrawal Escaping while still in contact Communication .

However , following heavy fighting Hostile_encounter the pressure on the Australians unexpectedly ceased Process_end after midnight , and parties of PVA were observed Perception_active beginning to withdraw Escaping .

By early morning the PVA attack had been checked Preventing_or_letting and 3 RAR had redeployed Placing to new positions in the paddy fields around the railway crossing north of Maenjung-dong .

Nonetheless , the 27th British Commonwealth Brigade succeeded in preventing Preventing_or_letting a PVA break-through at Pakchon , keeping Temporary_stay open vital withdrawal Escaping routes across the river and securing Getting the UN left Departing flank .

Suffering Bodily_harm significant casualties Catastrophe , the PVA offensive was halted Process_end the next day due Causation to logistic difficulties .

The PVA and KPA were temporarily forced Motion to withdraw Escaping north , while the UN successfully reinforced Cause_change_of_strength its positions Placing , holding Defending on the Chongchon Line .

Yet by late November the US Eighth Army was again forced Motion to withdraw Escaping after the PVA began Process_start their Second Phase Offensive , starting Process_start a long retreat Escaping south .

More than 88,000 rounds of Chinese People 's Volunteer Army ( PVA ) artillery fell Motion_directional on Outpost Harry .

During the 4 to 5 days prior to the initial attack on the outpost , PVA artillery and mortar fire increased Cause_change_of_position_on_a_scale from an average of 275 to 670 per day during daylight hours .

Anticipating this reaction , the Chinese People 's Volunteer Army ( PVA ) Commander Peng Dehuai planned Arranging a counteroffensive Attack , dubbed Name_conferral the `` Second Phase Campaign '' , against the advancing UN forces .

Hoping to repeat the success of the earlier First Phase Campaign Military_operation , the PVA 13th Army first launched Process_start a series of surprise attacks Attack along the Ch'ongch'on River Valley on the night of November 25 , 1950 at the western half of the Second Phase Campaign Military_operation ( ) , effectively destroying Destroying the Eighth United States Army 's right flank while allowing Preventing_or_letting PVA forces to move Self_motion rapidly into UN rear areas .

Hoping to repeat the success of the earlier First Phase Campaign Military_operation , the PVA 13th Army first launched Process_start a series of surprise attacks Attack along the Ch'ongch'on River Valley on the night of November 25 , 1950 at the western half of the Second Phase Campaign Military_operation ( ) , effectively destroying Destroying the Eighth United States Army 's right flank while allowing Preventing_or_letting PVA forces to move Self_motion rapidly into UN rear areas .

In the subsequent battles Hostile_encounter and withdrawals Escaping during the period of November 26 to December 2 , 1950 , although the US Eighth Army managed Control to avoid Preventing_or_letting being surrounded Surrounding by PVA forces Causation , the PVA 13th Army were still able to inflict Causation heavy losses Earnings_and_losses onto the retreating Escaping UN forces which had lost Earnings_and_losses all cohesion .

In the subsequent battles Hostile_encounter and withdrawals Escaping during the period of November 26 to December 2 , 1950 , although the US Eighth Army managed Control to avoid Preventing_or_letting being surrounded Surrounding by PVA forces Causation , the PVA 13th Army were still able to inflict Causation heavy losses Earnings_and_losses onto the retreating Escaping UN forces which had lost Earnings_and_losses all cohesion .

After a joint Collaboration Chinese People 's Volunteer Army ( PVA ) and KPA assault breached the UN defenses at Chuncheon on New Year 's Eve of 1951 , KPA V Corps attacked Attack US X Corps at Wonju while KPA II Corps harassed US X Corps ' rear by engaging in guerrilla warfare .

In the aftermath of the major Chinese People 's Volunteer Army ( PVA ) victory Earnings_and_losses at the Battle of the Ch'ongch'on River , the United Nations Command ( UN ) started Process_start to contemplate the possibility of evacuation from the Korean Peninsula .

To prevent Preventing_or_letting the PVA forces Hostile_encounter from overwhelming the defenders , the US Eighth Army now under the command Control of Lieutenant General Matthew B. Ridgway evacuated Escaping Seoul on January 3 , 1951 .

The battle Military_operation took place Process_start about a month after the People 's Republic of China entered the conflict Hostile_encounter and sent Sending the People 's Volunteer Army ( PVA ) 9th Army to infiltrate Attack the northeastern part of North Korea .