Question: Which event took place first, Operation Undertone or The Battle of the Ch'ongch'on River?
Sentence (from "Battle of Wawon"): The Battle of Wawon (Turkish: "Kunuri Muharebeleri" ), also known as the Battle of Wayuan (), was a series of delay actions of the Korean War that took place from November 27–29, 1950 near Wawon in present-day North Korea.
Relevant evidence: No