Since all battalions of the 5th Marines were to be involved either directly or indirectly in Operation CLAMBAKE, the initial planning and actual execution of the raid was to be carried out by the regimental commander, Colonel Walt. Clambake required especially thorough coordination of the heavy fire support since it was to be launched with a tank-artillery feint against several CCF positions (Hill 104, Kumgok, and Red Hill) generally west of the Ungok objective area. The two target hills were to be assaulted by reinforced platoons from Company A (Captain Don H. Blanchard) of the reserve battalion, 1/5, commanded by Lieutenant Colonel Jonas M. Platt, who was responsible for the later planning stages of the raid. It was anticipated that intensive air and artillery preparation on the feint objectives and movement of gun and flame tanks during the diversion would gain the element of surprise for the assault platoons. Thus the Marines hoped to take prisoners, the main purpose of the raid, and to kill enemy troops and destroy their defenses.
During the five weeks of preparation, every aspect of the maneuver was thoroughly reviewed and rehearsed. All participating units took part in the planning conferences. Routes were reconnoitered, mines cleared, and fire concentrations plotted and registered. MAG-12 pilots studied the target areas from the nearby Marine MLR. Six rehearsals, including practice in casualty evacuation, uncovered potential problem areas. Final rehearsal was held 1 February, with artillery and air preparation made against the feint objectives. Four close air support strikes were conducted that day and the next as part of the plan to divert enemy attention from the CLAMBAKE destruction mission.
Shortly after first light on 3 February, three platoons of tanks rumbled across the MLR to assault the feint area. A heavy “false” artillery preparation by 1/11 was also placed on the three western enemy hills as well as direct fire from gun and flame tanks. The two Marine assault forces, one against each hill, moved out armed with flamethrowers, 3.5-inch rockets, machine guns, grenades, satchel charges, bangalore torpedoes, and automatic weapons. Enemy forces occupying the positions made three separate counterattack attempts, which were blunted by Marine supporting arms. During the infantry attack, friendly air hovered on station and artillery fired continuous counterbattery and countermortar fire.
With the exception of the change of withdrawal route of one of the assault teams, the 5th Marines reported that the operation was carried out according to plan. Company A tanks had swung left across the frozen rice paddies to provide left flank security for the infantry and to interdict trenchlines that connected with the Ungok objective. Intense enemy fire lashed the armored vehicles as they approached Kumgok and Red Hill as well as those supporting tanks that remained on the MLR.[342] Air, artillery, infantry, and tanks produced an estimated 390 Chinese casualties (including 90 known KIA) in addition to damaged or destroyed trenchlines, tunnels, caves, bunkers, and weapons of the enemy. Marine losses were 14 killed and 91 wounded. One flame tank was lost.
[342] For a detailed account of the tank action in the CLAMBAKE raid see Col Clyde W. Hunter ltr to Dir MCHist, HQMC, dtd 6 Jun 70, in v. V, Korean comment file.
As in the case of the 1st Marines WAKEUP raid in November 1952, CLAMBAKE was important not so much in accomplishing its primary mission (actually, no POWs were taken) as in lessons learned. One of these was to reemphasize the fact that thorough preparation helped to ensure smooth coordination of infantry and supporting arms. In his report of the operation, Lieutenant Colonel Platt wrote, “minute planning to the last detail along with carefully executed rehearsals are basic to success in actions of this type.”[343] He further noted that “confidence and enthusiasm stimulated by the rehearsals are assets which cannot be overlooked.”[344] The battalion commander also commented on the importance of planning for both troop withdrawal and maintaining a flexible schedule of fires by supporting arms. Air,[345] artillery, and tanks all employed fire plans that could be readily adjusted to meet the changing tactical situation.
[343] 1/5 ComdD, Feb. 53, App. IVc, dtd 19 Feb 53, p. 5.
[344] Ibid.
[345] In order to assure better close air support during the assault; an SOP for the airborne tactical controller was proposed and drafted by MAG-12 for 1st MAW approval. The plan utilized the marking of targets by rocket and subsequent corrections to be made by the FAC. This enabled MAG-12 aircraft “to scramble, fly a CAS mission at the Division front and be back at the field at K-6 in approximately 40 minutes.” Col Wayne M. Cargill ltr to Dir MCHist, HQMC, dtd 8 Jan 70.
On the ground, flame was found to be the best weapon for neutralizing the well-fortified CCF caves. From Company A, 1st Tank Battalion (Captain Hunter) came information about Chinese 3.5-inch rocket launcher teams used in antitank defense. Several of these tank-killer teams had run down the trenchline holding small bushes in front of them. The enemy then boldly advanced through a hail of bullets to within 15–20 yards of the Marine tank before opening fire with their rockets. Short bursts of flame from headquarters tanks soon caused even the most intrepid to beat a hurried retreat.