Complex sentence: The Battle of Yongju took place on 21--22 October 1950 during the United Nations (UN) counter-offensive during the Korean War against the North Korean forces which had invaded South Korea.
Split into simpler sentences: The Battle of Yongju took place on 21--22 October 1950 during the Korean War. It was part of the United Nations (UN) counter-offensive against the North Korean forces which had invaded South Korea.