A second type of Marine close air support aided the mission of Marine infantrymen in western Korea during the summer of 1952. This was controlled radar bombing, which permitted delivery of aviation ordnance at night or under other conditions of limited or poor visibility. The Air Force had introduced the concept into Korea in January 1951, had tested and evaluated it in combat, and shortly thereafter had put it to good use against the Communist spring offensives that year. Based on a concept oriented towards deep support of troops in extended land campaigns, the Air Force system made use of 20-ton vans to house its ground components.[87]
[87] As an Air Force spokesman noted, “... the AN/MPQ-2 radars introduced into Korea in January 1951 were Strategic Air Command bomb scoring radars and not tactical equipment. This would explain the large vans.” Robert C. Futrell, Historian, Hist Studies Br USAF Hist Div, comments on draft MS, dtd 12 Oct 66. Dr. Futrell authored the definitive unclassified history of Air Force operations in Korea, previously cited as USAF, Korea.
The Marine equipment, on the other hand, was more mobile since it was to be employed close to friendly lines. Referred to as the MPQ-14,[88] the Marine radar bombing system was designed so that the largest piece could be put into a one-ton trailer. Major ground items were a generator power supply, a tracking radar, and a computer; the last essential component, an automatic bombing control, was mounted in the aircraft.
[88] These letters indicate first, the type of installation; next, the kind of electronic equipment; and finally, its purpose. In this case, M-mobile ground installation, P-radar, and Q-intended for a combination of purposes. The figure indicates the model number in the developmental history of the equipment.
Developed and hand built after World War II by Marines under Major Marion C. Dalby at the Naval Air Materiel Test Center, Point Mugu, California, the MPQ-14 was first used in Korea in September 1951. Initially, considerable mechanical difficulty was experienced with radar bombing, which affected the accuracy of the bombs, but later the system became sufficiently reliable to permit bomb drops within one mile of friendly lines. Subsequent use confirmed the tactical precision of the MPQ-14. By the middle of summer 1952, the Marines had obtained Fifth Air Force permission to use radar bombing, controlled by a forward observer on the ground, in a close support role.
Before this policy change took place another one, at a still higher command level, had occurred. On 23 June, FAF planes struck at eight North Korean hydroelectric plants in the central and northwestern part of the country. The attack represented a departure from the intense interdiction of enemy lines of communication (Operation STRANGLE) which, since May 1951, had characterized FAF support operations. The shift came about after a Far East Air Forces study on the effectiveness of the interdiction campaign had concluded, in part, that the program had been indecisive.[89]
[89] HistDiv; Air Univ, USAF, United States Air Force Operations in the Korean Conflict, 1 November 1950–30 June 1952, USAF Hist Study No. 72 (Washington, 1955), p. 159, hereafter USAF, Ops in Korea, with appropriate number. The Air Force operations were published in three books, numbered 72, 73, and 127.
For more than a year preceding the 23 June attack, the Fifth Air Force had concentrated its ground support efforts on the disruption of Communist communication lines so that the enemy would be unable “to contain a determined offensive ... or to mount a sustained offensive himself.”[90] During the lifetime of the doctrine, no major offensive had been launched by the enemy, and on this fact was based the claim for success of the interdiction program. Opponents, however, pointed out that despite this maximum FAF air effort, the Communists had built up their strength, including support areas immediately to the rear of their front lines and resupply installations. As the recent UN commander, General Matthew B. Ridgway,[91] told members of the Senate Committee on Armed Services on 21 May 1952, the same month that FAF had begun to shift its air effort away from interdiction, “I think that the hostile forces opposing the Eighth Army ... have a substantially greater offensive potential than at any time in the past....”[92]
[90] Futrell, USAF, Korea, pp. 435–436.
[91] General Mark W. Clark had succeeded Ridgway as UN Commander on 12 May 1952. Ridgway was to take over as the new Supreme Allied Commander, Europe, 1 June, replacing General of the Army Dwight D. Eisenhower, who was returning to the United States.