Marine support units—motor transport, tank, service, medical, aerial liaison (VMO/HMR)—were in the same general rear area, as was the headquarters of the U.S. 25th Infantry Division. The Marine Division CP continued to be located at Yongji-ri, although construction of a new site further south at Chormyon was due to be completed by engineer personnel on 1 October. The division railhead and truckhead remained, respectively, at Munsan-ni and Ascom City. To the left of the KMC sector was the 1st Amphibian Tractor Battalion. Still further west, separated from other units by the Han River, was the Kimpo Provisional Regiment, in its former wartime sector.

As the division OPLR regiment, the 5th Marines held a line 36,000 yards in length—about 21 miles—roughly corresponding to the front manned by three regiments during the war. The OPLR sector included the entire area in the divisional zone of responsibility north of the Imjin. Boundaries of the 5th Marines territory were the southern DMZ truce line on the west and north, the Samichon River to the east, and that major water barrier, the curving Imjin River, to the rear.

After establishment of the DMZ, the division occupied unfavorable low ground poorly suited to the defense and inferior to that held by the enemy—continuing the same situation that had existed during the period of stabilized combat operations in West Korea. Almost without exception the southern boundary of the DMZ prohibited the Marines from moving onto the commanding terrain, as the No-Pass Line was behind or along the reverse slopes of the high ground. On the other hand, in most cases the CCF had the advantage of having forward slope positions as well as the crests plus most of the commanding terrain in the area.

Communist territory in the northern DMZ sector included the former strongholds of Yoke, Bunker Hill, Carson, Reno, Vegas, Berlin, East Berlin and Warsaw. Within the Marine division postwar area were the Panmunjom Corridor and outposts Marilyn, Kate, the Boulder City hills, and the Hook. Much of the terrain between the major hill positions along the 5th Marines regimental front and the Imjin River consisted of low-rolling hills rising abruptly out of the rice paddies.

Construction of new positions and the defense system of the 5th Marines was based on several assumptions about enemy capabilities, made by G-2 and the new regimental CO, Colonel Rathvon McC. Tompkins, who had assumed command on 2 August. These were: that in the event of resumption of hostilities by the CCF the enemy would use his jet fighters and bombers in support of operations; that he would continue to have numerical superiority in artillery; and that the northern outpost regiment would have no reinforcement or surface resupply from units south of the Imjin.

The defense plan for the forward part of the 5th Marines sector in event of a resumption of hostilities called for furnishing patrols equipped with radios and FO teams to occupy Hills 155, 229, and 181. (Hill 155 was directly south of the DMZ in the 2/5 left battalion sector; Hills 229 and 181 were, respectively, just inside and just outside the southern boundary of the truce line in the center 1/5 sector.) From these three elevations the patrols would then have the mission of bringing down artillery fire on enemy concentrations and relaying communications about the situation to the friendly main attack force. Other critical hill masses in the OPLR regimental sector were Hill 126 (in the 3/5 eastern battalion sector, just inside the Marine side of the DMZ) and Hill 163, in the Hook area. The latter hill was not as suitable for defense since it was located south of the military demarcation line and was thus less accessible.

These hill masses so completely dominated the major enemy approaches through the division sector to the Imjin, the lower river crossing sites and bridges, that their occupation by Marine personnel was considered essential in the event of any attack. Hill 229, adjacent to the Chan-dang corridor and part of the 229-181 axis, was considered the most critical terrain feature in the entire northern section.

Key areas to the rear of the 5th Marines’ sector were the two operating bridges (Freedom in 2/5 territory and Libby on the 3/5 right) and the two interior crossing sites (Honker and Spoonbill). All provided access to the Imjin and division support units deployed on the south side of the river. In the event of threatened hostile attack, the Northern Regiment was under orders to destroy the bridges to prevent their use by the enemy on any attempted advance to the rear.

Strong perimeter defenses, called “Bridgehead Positions” were to be built by 5th Marines’ battalions. Two were to protect the two bridges and a third, to include both ferry sites. Between the forward defended localities and the rear bridgehead positions, alternate and secondary sites were organized to create mutually supporting defenses in depth. The bridgeheads were a combination of linear and strongpoint defense, capable of withstanding severe pressure.

Organization of the defensive positions in the 5th Marine sector was complicated both by peculiarities of the terrain and political restrictions due to proximity of the DMZ. In addition to the regiment’s excess frontage, the demilitarized zone immediately to the front precluded use of either aerial or motorized reconnaissance for early warning. Security measures for the OPLR were less than ideal. Neither proper patrols nor a covering force in front of the OPLR was possible; the best that could be done was to maintain patrols along the friendly side of the No-Pass Line.

As the regimental left battalion pointed out: “Location of the DMZ and the No-Pass Line made the trace of the OPLR follow an artificial and arbitrary line rather than that of the best terrain.”676 The most critical terrain feature in the sector, Hill 155, was located just outside the southern boundary of the DMZ. Although its possession was essential to successful defense of the OPLR and the bridgehead defense positions being developed to the interior and rear of the battalion sector, Hill 155 could not be occupied because of the armistice agreement. The solution to the problem was simply to occupy the best ground adjacent to the No-Pass Line.

Placement of automatic weapons was a factor of great importance in organizing the defensive positions. In order to accomplish the mission of an OPLR, weapons had to be situated to bring the enemy under fire at maximum ranges. Accordingly, machine guns and other weapons were placed on high ground well to the front. Some Marines commented that:

The problem of establishing depth to the defensive positions was never solved to the satisfaction of everyone. This was due primarily to the extended front which necessitated using more units for support elements than would normally be done. This situation was partly alleviated by establishing some unit defensive sectors further to the rear in the company areas.

Another difficulty was the inadequate allocation of ammunition: one-half JAMESTOWN load on position, and another half-load available at the regimental dump. The JAMESTOWN load unit had been developed for use in a stabilized defense situation where automatic weapons were aimed as the enemy came in close proximity to the MLR. On the other hand, OPLR machine guns and weapons were required to open up at maximum ranges and might well be fired for extended periods of time. It was calculated that A4 machine guns firing at medium rate (75 rpm) would expend the one-half JAMESTOWN load in 22 minutes, while an A1 machine gun at medium rate (125 rpm) would exhaust the same load in 13 minutes. A partial improvement was obtained by moving the ammunition loads from regimental to battalion dumps although the basic problem of limited allocation—shared also by rear infantry regiments—continued to exist.

An unique situation that had confronted the 2d Battalion and at times the adjoining 1st Battalion stemmed from the large numbers of Army engineer personnel building the nonrepatriate POW camp in the DMZ immediately west of the 2/5 sector. During August and the first part of September, the area in front of 2/5 had been used as a base camp for 5,000–7,000 construction personnel. Although their area was crowded with these additional units, the Marine battalions could not exercise any control over them. The Marines were still responsible for security of the sector, however. Presence of as many as 22,000 nonrepatriate CCF and NKPA prisoners as well as the Indian custodial forces further complicated the matter. It was noted that:

Camp construction and development of the new positions south of the river continued at a furious pace from August through early October. Since the new camp sites were in civilian populated areas, “it was necessary to secure real estate clearance before they could be occupied or improved.”679 After clearance was obtained on 29 July, division engineers immediately began work on five separate camps. These camp building activities and reconnaissance of assigned blocking positions continued until 10 August. At this time, construction began on the major blocking positions, so organized and developed as to be self-sustaining for several days. Whether squad, platoon, or company, all positions were organized using a perimeter type defense and were mutually supporting laterally and in depth. Connecting trenches, bunkers, ammunition holes, and tank slots were also built.

By early October, construction of the blocking positions was completed by the 1st Marines despite the fierce summer heat, the numerous rock formations in the area that were difficult to dig out with limited tools and demolitions, and the shortage of personnel due to units participating in the new series of division MARLEX exercises, resumed in October. Within three months, the Marine division had thus largely completed building of a solid defense in its new main battle position. The importance of maintaining combat readiness for any renewed hostility on the part of the enemy demanded continuing vigilance at all times.

Defense specifications throughout the 5th Marines northern general outpost sector called for some 1,560 individual fighting positions, 400 automatic weapons sites, 8 bunkered infantry OPs, 30 bunkered CPs, 15,400 yards of trenchlines, and 70,000 yards of protective and tactical wire. In construction of the MBP, all bunkers were so blended and camouflaged with the natural terrain that they were almost impossible to be seen.

To the division rear, the location of recoilless rifle positions, FDC bunkers, and tank slots in the blocking positions and bridgeheads was the major priority. In the antimechanized defense plan, tanks covered likely avenues of approach into the general outpost area and also overlooked critical river crossing sites. Wherever possible old firing positions which had been previously prepared to support the secondary lines WYOMING and KANSAS were utilized. By the end of the year, 204 tank firing positions had been emplaced throughout the Marine division sector.

Three rehearsals for the occupation of the main battle position were held by the 1st Marine Division in September. All division units, both combat and service, participated in these exercises. Tactical units were required to occupy the MBP and be fully prepared for combat on four hours’ notice; service units were to provide additional local security required for the elimination of enemy infiltrators or guerrilla agents. Divisional and I Corps test exercises indicated that three hours were necessary to man the MBP during daylight and approximately three and one half hours at night.

Postwar Employment of Marine Units in FECOM680

The 1st Marine Aircraft Wing Post-Armistice Plan, as part of Fifth Air Force operations, was effective at 2200, on 27 July. Its purpose, basically, was to insure that wing elements carried out provisions of the armistice and yet continued to maintain a high level of combat readiness in the uneasy truce period.

Two major operational restrictions had been imposed on the UNC air force by the armistice. The first was establishment of the “No-Fly Line” south of the Allied southern boundary of the DMZ. Any flight beyond that point had to be authorized by JOC and a barrier patrol was maintained by FAF to apprehend any violators of the truce provisions. The 1st MAW contribution to this aerial security team was night patrols performed by F3D-2s from VMF(N)-513 and radar-configured AD aircraft from VMC-1 (later, by the new VMA-251 squadron).

The second post-truce restriction, which affected wing logistic movements, limited the entry and departure of all Korean air traffic to five airfields. These aerial ports were K-2, K-8, K-9, K-14, and K-18. (K-16 was later added.) Neither K-3, the east coast home field of MAG-33 nor K-6, located just inland from the west coast and the site of MAG-12 operations, was included. All Marine traffic landed either at K-9 or K-2 for inventory, a procedure which subsequently developed into a bottleneck, and caused supply delays due to the substantial reduction in payload made to accommodate the necessary extra fuel due to greater overland distances between airfields. When the CG, 1st MAW requested that K-3 be made a port of entry to avoid the difficulties involved in use of the two FAF fields, ComNavFE disapproved the request with the following rationale:

Removal from Korea to Japan of operational combat aircraft for routine maintenance runs and their return thus had to be made through the same port of exit and reentry. Inspections were conducted by the USAF combat aircraft control officer at the port.

The post-truce 1st MAW mission, in part, comprised the following:

The strict interpretation of replacing combat aircraft, armored vehicles, weapons, and ammunition that were destroyed, worn out, or used up during the period of armistice was, of course, due to the sensitive political considerations. It was felt that replacement of combat equipment by UNC forces:

In August, postwar procedures were mapped out for 1st MAW personnel, as part of the overall quota limitations prescribed by FECOM (Far East Command) through FEAF and FAF echelons. A 1st MAW headquarters section, designated as 1st MAW, rear echelon, was established at Itami AFB, Japan, two hours’ flight from Korea. All incoming or outgoing aviation personnel on permanent change of station orders were to report to the rear echelon, 1st MAW. Announcement of Marine Corps plans to initiate future postwar rotation on a stretch-out basis (for both air and ground personnel) was also made in August. Preliminary plans called for changing the current 11-month combat tour in Korea to 14 months by March 1954, and possibly 16-month tours by July 1954, if extension of Korean service proved necessary. As with division personnel, monthly cumulative arrivals were not to exceed the number of departing aviation Marines. The quota set by FEAF for 1st MAW rotation for the month of August was 600, compared to the Marine division quota of 3,000 for ground personnel.

With the 1st Marine Division engaged for an unknown length of time in its postwar mission as an occupation force and 1st MAW units continuing to operate under FAF in Korea, new Marine ground and air units were assigned to the Far East theater shortly after the conclusion of Korean hostilities. On 23 July, the 3d Marine Division, together with supporting air units, was readied for deployment from Camp Pendleton to Japan the following month. On 13 August the division CP was opened afloat and units proceeded to Japan between 16–30 August. The mission of this division and the two major air units, MAGs-11 and -16, was to maintain a high state of readiness in the Far East Command and to assist in the air defense of Japan. As explained by the Commandant, their redeployment was accomplished “in order to provide the amphibious capability which is an important element of national strategy in that predominantly maritime theater.”684

The new Marine units thus joined in the Pacific, the 1st Provisional Marine Air-Ground Task Force685 that had been activated in Kaneohe, Hawaii in January of 1953. Commanded by Brigadier General James P. Risely, it was to include a headquarters company, reinforced regiment, and reinforced aircraft group. The special task force was designated as a hard-hitting, air-ground team that could respond immediately as a force-in-readiness to any emergency in the Pacific area.

Commanded by Major General Robert H. Pepper, the 21,100-man 3d Marine Division was called the “Three-Dimensional Division,” in reference to its training in airborne, amphibious, and atomic warfare. Within six months, its components were to stretch from Kobe to Tokyo, with division headquarters and the 9th Marines at Gifu, the 4th Marines at Nara, and other units at Otsu.

New Marine air units, which included Marine Transport Squadron 253 and Marine Observation Squadron 2, as well as MAGs-11 and -16, all came under 1st MAW operational control. Commanded by Colonel John D. Harshberger, the all-jet MAG-11, formerly based at Edenton, N.C., arrived at NAS Atsugi on 10 September. It comprised three F9F squadrons, VMFs-222, -224, and -314. Also at Atsugi, the Marine Corps aerial gateway to Japan, was the new transport squadron, VMR-253, commanded by Lieutenant Colonel Carl J. Fleps, which reported in to CG, 1st MAW, on 16 August. Following numerous FMFPac requests for additional air transport capability, the Commandant had authorized transfer of the squadron from El Toro to assist the veteran wartime carrier VMR-152 in the enormous postwar airlift program.

Flying new R4Q Fairchild Packets, which could carry 42 troops, the squadron from August to May 1954 logged more than 5,000,000 passenger miles in transporting Marine replacements for the 1st and 3d Marine Divisions. Additional air capability was provided by Marine Helicopter Transport Group 16 (at Hanshin AFB) under Colonel Harold J. Mitchener, with its two HRS-2 (HMR-162, HMR-163) and service squadrons (MAMs-16, MABS-16) and VMO-2, commanded by Major William G. MacLean (based at Itami). Both units reported to 1st MAW and FECOM on 13 August.

Major command changes within the 1st MAW that month were: Brigadier General Verne J. McCaul, vice Brigadier General Alexander W. Kreiser, Jr. as ACG, 1st MAW, effective 16 August; and Colonel William F. Hausman, vice Colonel Carney, CO, MAG-12, on 8 August. (The new MAG-33 CO, Colonel Smith, had succeeded Colonel Stacy in late July.)

In the immediate post-armistice period, extensive training programs were instituted by MAGs-12 and -33 to maintain high operational efficiency. Marine aircraft remained on JOC alert as required by the Fifth Air Force and flew training missions scheduled by 1st MAW and FAF. These consisted of practice strikes against heavily-defended targets, practice CAS for Eighth Army units, GCI (ground control intercept) flights under MGCIS-3 control, and bombing practice using the Naktong Bombing Range. Other training sorties were scheduled in reconnaissance navigation, weather penetration, determining fuel bingos,686 target location and identification, air defense patrolling, and coordination of tactical procedures in the target area. The training schedules provided a well-balanced indoctrination program for new squadron flight leaders, pilots, radar operators, and other crew members arriving in Korea on the postwar personnel drafts.

A new work day schedule of 0700–1500 implemented in August made more time available for athletics, swimming, studying, and R&R (Rest & Recreation). That same month the MAG-12 softball team won the Fifth Air Force “All Korea” softball championship. Following this achievement, the team left for Japan to compete in the FAF “Far East” softball tournament which included teams from all the major Pacific bases. Subsequently, the K-6 players “disguised in Air Force uniforms, went onward and upward to become FEAF champions in September.”687 MAG-33 pilots, meanwhile, participated in Operation SPYGLASS, a FAF training exercise in August and Operation BACK DOOR, the following month. Both emphasized interception flying and work with GCI squadrons. As “aggressors,” the Pohang-based airmen made simulated attacks on South Korean targets “defended” by Air Force and other land-based Marine units. In October, MAG-33 pilots flew CAS missions for the 1st Marine Division training problem, MARLEX IV, a battalion landing exercise staged by 1/7 on Tokchok-to Island. Beginning that month a new procedure was inaugurated by MAG-33 and the recently-arrived MAG-11. Every week, four MAG-11 pilots came to Korea for a week of orientation flying with a MAG-33 squadron to gain a better picture of typical flying conditions in the Korean theater.

Early in 1955 the 1st Marine Division, which had been in the Korean front lines almost continuously since September 1950, returned to Camp Pendleton. Redeployment by echelons began in February. By June, all units had returned to CONUS. The transfer from Korean occupation duty was effected in order that the division’s “valuable capability as a highly trained amphibious force in readiness may be fully realized.”688 Now under Major General Merrill B. Twining,689 the division had been a part of Eighth Army occupying postwar defense positions in Korea until its relief on 17–18 March 1955 by the U.S. 24th Infantry Division.

In addition to its official mission in the Eighth Army line, the 1st Marine Division had conducted an active small-unit amphibious training program during its postwar Korea duty. All but two of its infantry battalions had carried out assault landings on Tokchok-to, off the Korean west coast south of Inchon, prior to its departure for the United States. The 3d Marine Division had also conducted an active training program, with numerous small-unit exercises and regimental landings staged at Iwo Jima and Okinawa as part of its continuous readiness conditioning.

For Marine air personnel, their official departure from Korea following the 1st MAW wartime assignment there, came the next year. Beginning in June 1956, initial units of the Marine aircraft wing were withdrawn from Korea and relocated at NAS Iwakuni, Japan. Plans called for the wing, then under Brigadier General Samuel S. Jack690 and occupying bases in both Korea and Japan, to be permanently headquartered at Iwakuni and revert to CinCPacFlt control. The wing remained on station in the Far East as a component of postwar United States defense strength in that area.

The prewar Fifth Air Force and Eighth U.S. Army commands, under which Marine Corps air and ground units had functioned during the Korean War, were permanently deployed in the Far East as operative military echelons. EUSAK-FAF transferred from its wartime JOC location at Seoul to Osan-ni in January 1954 and in September of that year relocated to Nagoya, Japan. Eighth Army headquarters remained at Seoul.

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