The Battle of Onjong (Korean: 온정리 전투), also known as the Battle of Wenjing (Chinese: 温井战斗; pinyin: Wēn Jǐng Zhàn Dòu), was one of the first engagements between Chinese and United Nations forces during the Korean War. It took place around Onjong in present-day North Korea from October 25 to October 29, 1950. As the main focus of the Chinese First Phase Campaign, the Chinese 40th Corps conducted a series of ambushes against the Republic of Korea II Corps, effectively destroying the right flank of the United States Eighth Army while stopping the UN advances north toward the Yalu River.