After the Inchon landings on 15 September, the North Korean forces besieging the Pusan Perimeter began to retreat. The 21st Regiment broke out of the perimeter on 19 September. In a rapid advance northward, it took Waegwan, Kumchon and Taejon. The regiment crossed the 38th parallel north in mid-October. At the peak of its advance on 2 November, the regiment was 17 miles south of the Chinese border.