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|Next: Battle of Chosin Reservoir|
|Battle of the Ch'ongch'on River|
|Conflict: Korean War|
|Date: 25 November-2 December 1950|
|Place: Ch'ongch'on River, North Korea|
|Outcome: Decisive Chinese victory|
After the Battle of Inchon and the Second Battle of Seoul, the US Eighth Army rapidly advanced towards the China-North Korea border along the Yalu River, overrunning the North Korean capital of Pyongyang and forcing the North Korean government to go into exile. The Chinese leader Mao Zedong was alarmed by this, so he decided to activate the People's Volunteer Army and ordered it to intervene in Korea. Between 25 October and 4 November, the Chinese won a series of battles around Onjong and Unsan, forcing the US and South Korean forces to retreat back to the Ch'ongch'on River. MacArthur mistakenly believed that Chinese forces were not operating in Korea on a large scale, believing that only 30,000 Chinese troops could remain hidden in the hills. In addition, he had the UN warplanes bomb the bridges over the Yalu River to disrupt Chinese troop movements, and he launched the "Home-by-Christmas Offensive" on 24 November 1950 with the goal of routing the last Chinese and North Korean forces on the peninsula. However, there were already 180,000 Chinese troops in Korea by that time, and the Chinese general Peng Dehuai planned a two-pronged offensive at the Chosin Reservoir and the Ch'ongch'on River.
The Chinese launched a series of surprise attacks along the Eighth Army's right flank on the night of 25 November 1950, destroying the army's weak right flank (which consisted mostly of South Korean troops). Chinese forces moved into the UN's rear areas, and the Eighth Army suffered heavy losses as the Chinese 13th Army attacked the retreating UN forces as they withdrew to the 38th Parallel. The battle was the peak of the Volunteer Army's performance in Korea, and Mao Zedong would unwisely order his generals to invade South Korea, breaking the fragile communist supply lines. The Chinese offensives of early 1951 would not meet as much success as their offensives of winter, 1950, and the war would turn into a stalemate.