At about 2000, green flares and bugle calls announced the approach of the Chinese from the north of the 1st Battalion, 1st Marines who were defending a height later called “Horseshoe Ridge.” Clashing cymbals while shouting and chanting, “Awake Marine!” the attackers came in waves. The defenders were subjected to a rain of hundreds of grenades and were forced to pull back 50 yards to establish a new line. The attacks continued for four hours until daybreak when Marine close air support forced the enemy into concealment.