With Lieutenant-General Matthew Ridgway assuming the command of the U.S. Eighth Army on 26 December, the PVA and the KPA launched their Third Phase Offensive (also known as the "Chinese New Year's Offensive") on New Year's Eve of 1950. Utilizing night attacks in which UN Command fighting positions were encircled and then assaulted by numerically superior troops who had the element of surprise, the attacks were accompanied by loud trumpets and gongs, which fulfilled the double purpose of facilitating tactical communication and mentally disorienting the enemy. UN forces initially had no familiarity with this tactic, and as a result some soldiers panicked, abandoning their weapons and retreating to the south. The Chinese New Year's Offensive overwhelmed UN forces, allowing the PVA and KPA to conquer Seoul for the second time on 4 January 1951.

What is the Third Phase Offensive also known as?