Even before the Chinese had made their coordinated attack against Hill 122 in the midafternoon of the 12th, the 1st Marines had implemented a plan of action to assure that the critical position would remain in Marine hands. In addition to the movement of Company I/3/1 to reinforce Bunker Hill and of Company I/3/7 as its relief on the MLR, a precautionary displacement was also made of the 3/1 reconnaissance platoon to Hill 124 to tie in that terrain feature with both Bunker and JAMESTOWN and thus consolidate the defense north of the MLR and west of Bunker. (See [Map 11].)
MAP 11 K. WHITE
BUNKER HILL AREA
2300, 12 AUGUST 1952
Other activities behind the line aimed at making the Marine position on the newly seized hill more tenable. As one step in this direction, General Selden shifted most of his reserve into the zone of action. Before the end of the day remaining units of 3/7 were placed under operational control of 3/1, and 2/7 was attached to Colonel Layer’s reserve. The 7th Marines was directed to place its 4.2-inch mortars on call to the 1st Marines. Priority of artillery support went to the Bunker Hill regiment. Within the 1st Marines, the regimental commander moved two provisional platoons (118 Marines) of the reserve 1st Battalion to the 3d Battalion sector. All 81mm mortars in 1/1 were sent to the left battalion. The fire plan also called for employment of all the 60mm mortars that could bear on the crest of 124–122, with 81mm and artillery box-me-in barrage fires on the ridge and flanks.
Machine guns from the MLR were assigned missions on the crest of Bunker Ridge and 4.5-inch ripples were planned on the deep enemy approaches. Gun and flame tanks were to protect the right flank of Hill 122 where the steep draw between Bunker and the MLR offered the most dangerous approach into Bunker Hill. Supplies and fortification materials, meanwhile, were being carried forward and casualties taken to the rear by the relief party. Although 3/1 initially reported that the Bunker Hill fighting had resulted in 58 killed or wounded Marines, a later battalion count showed this number to be 34—5 killed and 29 wounded.
Most of the casualties had been caused by hostile shelling. Although the Hill 122 reverse slope afforded some cover from the Chinese artillery and mortars, the positions on the crest did not offer any protection, so Marines continued their trenchworks and other defensive preparations at a rapid pace and supporting fires were registered by 1900. The approach of night was certain to bring renewed Communist attempts to capture Bunker Hill.
At 2000, Lieutenant Colonel Armitage reported to division that his force on Hill 122 occupied the entire reverse slope and that the Marine of I/3/1 and B/1/1 were digging in and consolidating their scant defenses. Enemy shells were still falling on both Bunker and Hill 124. Company commanders forward of the MLR estimated that as many as 400 Chinese occupied the ridge on the other side of the slope from the Marines. Since the crest of the long Hill 124–122 ridgeline was fairly level, the gentle incline of the Bunker rear slope permitted defending Marine units excellent fields of fire to the ridge crest, a major consideration in the 3/1 battalion commander’s decision to adopt a rear slope defense. Moreover, the top of the ridge could be swept with direct fire from the MLR as well as supporting weapons from the two nearest companies on JAMESTOWN. Opposing Marine and Chinese forces were thus lined up for a continuation of the battle for Bunker Hill.
It appeared that the Chinese wished to attempt a diversionary tactic of their own. To draw attention away from Hill 122 they engaged a Marine outpost east of Bunker and a KMC ambush far to the left before attacking Bunker again. In the KMC sector, shortly after 2300, an enemy infantry platoon walked into a trap near the eastern edge of the Sachon and 500 yards south of the Munsan-ni-Kaesong rail line. The brief fire fight lasted only 10 minutes before the Chinese broke contact.