The series of events that caused General Kean to change the direction of De Chow's attack toward Kŏmam-ni began at 0100, 3 September. The 1st Battalion, 35th Infantry, protruded farther westward at this time than any other unit of the U.N. forces in Korea. Back of its positions on Sibidang-san the main supply route and rear areas were in enemy hands, and only in daylight and under escort could vehicles travel the road.
On Sibidang-san the battalion had held its original positions after the heavy fighting of pre-dawn 1 September, completely surrounded by barbed wire, booby traps, and flares, with all supporting weapons inside its tight perimeters. The battalion had the advantage of calling by number for previously zeroed and numbered protective fires covering all approaches, which were quickly delivered. An hour after midnight an unusually heavy enemy assault struck the battalion.