The Korean Marines, holding down the western flank of the three mainland regimental sectors in the 1st Marine Division line, also received a share of the enemy’s attention. At dusk on 5 September, Chinese barrages began to smash Outpost 37,[219] the first of a trio of positions that would merit hostile attention for the next 22 hours. Throughout the following day the Chinese continued their mortar and artillery fire against Outposts 37 and 36, and the regimental observation post located on Hill 155 (also called Hill 167) to the rear of the MLR. (See Map 13.) The heaviest enemy fire was directed against OP 36, a small rise in the low land terrain midway between the Sachon River, on the west and the Munsan-ni-Kaesong rail line, 600 yards to the east. [219] Contemporary records of the 1st KMC Regiment for 1952–1953 identify this as Outpost 37. Current reviewer comments refer to this hill as OP 67. LtCol Kim Yong Kyu, ROKMC, ltr to CMC, HQMC, dtd 5 Jul 67. At 1605 a 50-round barrage struck OP 36. After this harassing fire there was a lull until 1810 when Chinese artillery and mortars again resumed a steady pounding of the three positions. One hour later enemy soldiers hit both outposts. Twice the attacking company assaulted OP 37 but neither effort represented, in the view of the defenders, a serious attempt at capture. Less than a mile south at OP 36, however, the enemy motive appeared to be quite different. Crossing the Sachon just north of the Freedom Gate Bridge (also known as the highway bridge), the Communist infantry moved to assault positions on the west, north, and northeast sides of the outpost. At 1910, the Chinese began their first rush. It was repulsed, as was a second one. Another artillery barrage, joined this time by tank fire, preceded the third attempt. At this point communications went out at the besieged outpost. At 2150, a squad leader from OP 36 reached the 10th Company CP to report that his position had fallen. In 30 minutes a communications link was reestablished with the outpost. The defending Koreans reported that although enemy troops had overrun much of the hill, they had subsequently withdrawn, apparently because their losses had been so heavy.