It was in this direction that an enemy force, estimated at reinforced battalion strength, headed during the early morning fighting on Hill 122. At 0330, the struggle for possession of the height had reached the climax. For an hour the issue remained in doubt. Then, as the Chinese small arms fire decreased, the tempo of the enemy’s artillery shelling increased. This, the division correctly deduced, announced the beginning of a temporary Communist withdrawal from Bunker Hill.
Although the immediate danger of the enemy onslaught had ended for the time being, Marines to the rear of the JAMESTOWN Line stepped up their defensive preparations. Division, regimental, and battalion operational plans were put into effect to prevent a Chinese victory. The seriousness of the situation on the 1st Marines right flank at Stromboli early on 13 August had resulted in the movement of one company of 5th Marines into blocking positions behind the MLR near the left regimental boundary. To the south of Bunker Hill, relief and replacement units from the division reserve, ordered into action late the previous day, maneuvered into position to strengthen the regimental front. One of these relief units, G/3/7, under command of Captain William M. Vanzuyen, had just deployed from its assembly area to pass through the ranks of an MLR company and take over the Bunker Hill positions. The Marines’ situation on Hill 122 had deteriorated so rapidly, however, that the 3/1 commander rushed two reinforced squads forward from I/3/7, the nearest MLR unit.
The Company G reinforcement unit jumped off from JAMESTOWN and arrived at Bunker shortly after sunup, where it reinforced Captain Connolly’s positions during the height of the battle for possession of Hill 122. Not long after, the Chinese initiated their withdrawal under cover of increased artillery and mortar barrages. As they left, the Communists policed the battlefield in their typically thorough manner. A Marine platoon that swept the northern slope of Bunker failed to find any enemy bodies in this area so recently abandoned by the Chinese, but did take under fire and kill seven enemy that had remained on Hill 122.
Before I/3/1 had sent one of its platoons to reconnoiter the far side of Bunker Hill, Lieutenant Colonel Armitage ordered H/3/7, under Captain John G. Demas, forward to relieve friendly forces at the contested height. The exchange of units was completed before noon of the 13th. By late afternoon, except for Company H, all 2d and 3d Battalions, 7th Marines units that had moved up to reinforce the 1st Marines were on their way back to the regimental reserve area. At this time the 1st Marines CO, Colonel Layer, reported to General Selden that the Bunker Hill action during 12–13 August had resulted in 24 Marines killed and 214 wounded. On the right, in the 2d Battalion sector, an additional 40 Marines were listed as casualties, including 7 killed in the Stromboli defense. Chinese known dead numbered 210, plus an estimated 470 killed and 625 wounded.[184] Artillery and aerial observers reported that between 1500 on the 12th and 0600 the following morning an estimated 5,000 to 10,000 rounds of enemy fire had fallen on 1st Marines positions, the “heaviest incoming fires received by the Division since coming into the present sector.”[185]
[184] 1stMarDiv PIR 658, dtd 14 Aug 52.
[185] Selden, Div Staff Rpt, p. 19.
The number of casualties from the Bunker Hill action was to increase further that same day with a renewed attack on the outpost. Before the Chinese again engaged Hill 122, however, they made a diversionary attack on the western flank at the extreme left of the 3/1 sector. At dusk on 13 August, the enemy shelled the Company G Marines at COP 2, the critical height overlooking the Panmunjom peace corridor. The shelling caused several casualties and lasted 90 minutes. Towards the end, Communist infantrymen moved forward and fired on the outpost. At about the same time, Company H personnel emplaced on the MLR to the rear of COP 2 began to receive artillery rounds in preassault proportions.
A ground attack in this western end of the 3/1 sector did not materialize, however. Instead, the Chinese resumed their attack on Bunker Hill. Since their temporary withdrawal early on the 13th, the CCF had repeatedly sent mortar and artillery barrages against the bastion to harass its new occupants. On occasion these well-aimed mortar rounds found their mark. Mortars interdicting a trail used for resupply of the Hill 122 defenders did inflict some casualties on two groups rushing emergency supplies forward from the MLR.
At 2100, while continuing his shelling of the left end of the 3/1 sector, the enemy lifted his preparation on Hill 122 to permit a CCF reinforced company to make a new assault there on the Marine defenders. Captain Demas called for box-me-ins to seal off his positions and illumination shells to help locate the enemy force. Utilizing the draw to the east of Hill 58A, the Chinese proceeded west to Bunker where they pitted one platoon against the center of the Company H, 3/7 line and another against the right flank. Defensive fires momentarily held off the intruders, although some were able to break through to the Marines’ fighting positions.
Those enemy troops who penetrated the Marine defenses were quickly eliminated by grenades and small arms fire. Unable to weaken the Marine defenses any further and by now sustaining sizable casualties from unrelenting Marine artillery and mortar concentrations, the Communists withdrew at 2215. Marine defenders estimated they had killed 175 enemy during this latest encounter; a firm count of 20 bodies were found on the shell-torn slopes. Company H casualties, all from enemy mortar and artillery fire, were 7 killed and 21 wounded.[186] Enemy incoming was again heavy during this period, with a reported 3,000 rounds falling in the sector.