The battle Hostile_encounter ended Process_end in a victory for the United Nations after large numbers of United States Army ( US ) and Republic of Korea Army ( ROK ) troops repelled Defending a strong Korean People 's Army ( KPA ) attack .

Republic of Korea Army ( ROK ) units had been unsuccessfully resisting Defending advances by the North Korean Korean People 's Army ( KPA ) in the region when they were reinforced Cause_change_of_strength by the United States Army 's 25th Infantry Division , newly arrived in Arriving the country .

Forces of the South Korean Republic of Korea Army ( ROK ) , supported Supporting by the United States Navy and United States Air Force ( USAF ) , defended Defending the eastern coast of the country as a part of the Pusan Perimeter .

For two weeks KPA and ROK units fought Hostile_encounter in several bloody back-and-forth battles Hostile_encounter , taking Conquering and retaking Conquering ground in which neither side was able to gain Getting the upper hand .

It followed a week of fighting Hostile_encounter between the Korean People 's Army ( KPA ) 13th Division and the Republic of Korea Army 's ( ROK ) 1st Division along the latter 's last defensible line in the hills north of the city .

Reinforcements Cause_change_of_strength , including the US Army 's 27th and 23rd Infantry Regiments were committed Commitment to bolster Cause_change_of_strength the ROK defenses .

For another week , KPA divisions launched Process_start all the troops they had in massed attacks Attack against the ROK and US lines .

The fighting Hostile_encounter was fierce with many casualties on both sides , particularly where the KPA and ROK fought Hostile_encounter one another .

The repeated attacks Attack eventually broke Process_start and pushed Causation back the ROK forces Military_operation .

The battle Hostile_encounter ended Process_end in a victory for the UN after large numbers of US Army ( US ) and Republic of Korea Army ( ROK ) troops were able to repel Defending the repeated attacks Attack of two North Korean Korean People 's Army ( KPA ) divisions .

On December 31 , 1950 , the Chinese 13th Army attacked Attack the Republic of Korea Army ( ROK ) 's 1st , 2nd , 5th and 6th Infantry Divisions along the 38th Parallel , breaching Damaging UN defenses Defending at the Imjin River , Hantan River , Gapyeong and Chuncheon in the process .