[9] The 1st KMC Regiment was again attached to the Marine Division on 17 March 1951 and remained under its operational control for the remainder of the war. CinCPacFlt Interim Evaluation Rpt No. 4, Chap 9, p. 9-53, hereafter PacFlt EvalRpt with number and chapter.
Once again, in May, the Marine division was assigned to the U.S. X Corps, east of the IX Corps sector. Shortly thereafter the Communists launched another major offensive. Heavy casualties inflicted by UNC forces slowed this new enemy drive. Marine, Army, and Korean troops not only repelled the Chinese onslaught but immediately launched a counteroffensive, routing the enemy back into North Korea until the rough, mountainous terrain and stiffening resistance conspired to slow the Allied advance.
In addition to these combat difficulties, the Marine division began to encounter increasing trouble in obtaining what it considered sufficient and timely close air support (CAS). Most attack and fighter aircraft of the 1st MAW, commanded by Major General Field Harris[10] and operating since the Chosin Reservoir days under Fifth Air Force (FAF), had been employed primarily in a program of interdicting North Korean supply routes. Due to this diversion of Marine air from its primary CAS mission, both the division and wing suffered—the latter by its pilots’ limited experience in performing precision CAS sorties. Despite the difficulties, the Marine division drove northward reaching, by 20 June, a grotesque scooped-out terrain feature on the east-central front appropriately dubbed the Punchbowl.
[10] Command responsibility of 1st MAW changed on 29 May 51 when Brigadier General Thomas J. Cushman succeeded General Harris.
Eighth Army advances into North Korea had caused the enemy to reappraise his military situation. On 23 June, the Russian delegate to the United Nations, Jacob Malik, hinted that the Korean differences might be settled at the conference table. Subsequently, United Nations Command and Communist leaders agreed that truce negotiations would begin on 7 July at Kaesong, located in West Korea immediately south of the 38th Parallel, but under Communist control. The Communists broke off the talks on 22 August. Without offering any credible evidence, they declared that UNC aircraft had violated the neutrality zone surrounding the conference area.[11] Military and political observers then realized that the enemy’s overture to peace negotiations had served its intended purpose of permitting him to slow his retreat, regroup his forces, and prepare his ground defenses for a new determined stand.
[11] The Senior Delegate and Chief of the United Nations Command Delegation to the Korean Armistice Commission, Vice Admiral C. Turner Joy, USN, has described how the Communists in Korea concocted incidents “calculated to provide advantage for their negotiating efforts or for their basic propaganda objectives, or for both.” Examples of such duplicity are given in Chapter IV of his book, How Communists Negotiate (New York: The MacMillan Company, 1955), hereafter Joy, Truce Negotiations, quoted with permission of the publisher. The quote above appears on p. 30.
The lull in military offensive activity during the mid-1951 truce talks presaged the kind of warfare that would soon typify the final phase of the Korean conflict. Before the fighting settled into positional trench warfare reminiscent of World War I, the Marines participated in the final UN offensive. In a bitter struggle, the division hacked its way northward through, over, and around the Punchbowl, and in September 1951 occupied a series of commanding terrain positions that became part of the MINNESOTA Line, the Eighth Army main defensive line. Beginning on the 20th of that month, it became the primary mission of frontline units to organize, construct, and defend positions they held on MINNESOTA. To show good faith at the peace table, the UNC outlawed large-scale attacks against the enemy. Intent upon not appearing the aggressor and determined to keep the door open for future truce negotiations, the United Nations Command in late 1951 decreed a new military policy of limited offensives and an aggressive defense of its line. This change in Allied strategy, due to politico-military considerations, from a moving battle situation to stabilized warfare would affect both the tactics and future of the Korean War.
Even as Allied major tactical offensive operations and the era of fire and maneuver in Korea was passing into oblivion, several innovations were coming into use. One was the Marine Corps employment of helicopters. First used for evacuation of casualties from Pusan in August 1950, the versatile aircraft had also been adopted by the Marine brigade commander, General Craig, as an airborne jeep. On 13 September 1951, Marines made a significant contribution to the military profession when they introduced helicopters for large-scale resupply combat operations. This mission was followed one week later by the first use of helicopters for a combat zone troop lift. These revolutionary air tactics were contemporary with two new Marine Corps developments in ground equipment—body armor and insulated combat boots, which underwent extensive combat testing that summer and fall. The latter were to be especially welcomed for field use during the 1951–1952 winter.
Along the MINNESOTA Line, neither the freezing cold of a Korean winter nor blazing summer heat altered the daily routine. Ground defense operations consisted of dispatching patrols and raiding parties, laying ambushes, and improving the physical defenses. The enemy seemed reluctant to engage UN forces, and on one occasion to draw him into the open, EUSAK ordered Operation CLAM-UP across the entire UN front, beginning 10 February. Under cover of darkness, reserve battalions moved forward; then, during daylight, they pulled back, simulating a withdrawal of the main defenses. At the same time, frontline troops had explicit orders not to fire or even show themselves.[12]
[12] Col Franklin B. Nihart comments on draft MS, Sep 66, hereafter Nihart comments.