The Republic of Korea usually called South Korea , North Korea becomes communist and called theirselves the democratic people's of korea
September to October
UN army chased the retreating North Koream troops across the 38th parallel in to North Korea.
North Korea went to the 38th parallel that divided north and South Korea and attacked South Korea.
The u.s sent troops to South Korea to help them fight against North Korea .
UN troops approached the Yalu river, the border between North Korea and china , Korea seemed as if it was becoming a single country again .the Chinese had other ideas. 300,000 Chinese troops joined the war on the side of North Korea.