At 02 : 00 , B Company was attacked . A truck stopped at the bottom of the hill , a whistle sounded , then came a shouted order , and North Korean soldiers started climbing the slope . The hills on both sides of B Company were already under attack as was also Hill 311 , a rugged terrain feature a 1 @.@ 5 miles ( 2 @.@ 4 km ) from the river and the North Koreans ' principal immediate objective . The North Koreans apparently were not aware of the Task Force Manchu group lower down on the hill and it was not attacked during the night . But higher up on Hill 209 the North Koreans drove B Company from its position , inflicting very heavy casualties on it . Sheen led one group of soldiers back to friendly lines on 4 September .