Chapters:

1. To Korea by Sea
2. Policy and its Instruments
3. War Begins
4. Help on the Way
5. Into the Perimeter
6. Holding the Line
7. Back to the Parallel
8. On to the Border
9. Retreat to the South
10. The Second Six Months
11. Problems of a Policeman
12. Two More Years

A Note on Source Material

Glossary of Naval Abbreviations

• Part 1. February 1951: Back to the Han
• Part 2. March- April 1951: On to the Parallel
• Part 3. April-May 1951: the Communist Spring Offensive
• Part 4. June-July 1951: North to Kaesong
• Source Notes

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Part 3. April–May 1951: The Communist Spring Offensive

          The enemy offensive broke on the evening of 22 April with a thrust down the center by the Chinese 20th Army. South of Kumwha the ROK 6th Division collapsed under the weight of the attack, and as the enemy poured through the gap between the Marines and the 24th Infantry Division, General Van Fleet ordered a withdrawal. Four days went by before the assault was checked, and in this interval, with the enemy out in the open and moving, more than a thousand close support sorties by Fifth Air Force and carrier-based aircraft inflicted very heavy casualties.

Map 24. Communist Offensive and U.N. Advance, 21 April–30 June 1951 Click on map for higher resolution image (220 KB).

          The attack in the center and the U.N. retirement which followed had opened the valley of the Pukhan and the Chunchon-Seoul road. On the 26th, therefore, the Communists launched their main effort in an attempted double envelopment of Seoul, in which one prong was pushed down the Pukhan valley, while in the west an attempt was made to ferry troops across the Han onto the Kumpo peninsula. Both moves failed. The eastern threat to the capital was checked by the 24th and 25th Divisions, while on the Han a busy day of strafing by aircraft of the West Coast Carrier Element limited the arrivals to a number easily dealt with by the ROK Marine battalion defending the Kumpo peninsula. In the end the enemy advance in the west central sector reached a maximum of about 30 miles; east of the Hwachon Reservoir the Communists captured the town of Inje on the Hongchon-Kansong road; on the east coast they moved forward some five miles. But despite casualties estimated at ten times those of the U.N. no decisive advantage had been gained, and by the 29th the front was stabilized once more.

          Once again the enemy offensive brought an immediate response from U.N. naval forces. On 23 April Task Force 77 began a ten-day sustained effort in support of the battleline. On the next day the first of a series of amphibious feints was carried out. On the 26th the threat to Seoul brought another evacuation alert at Inchon: cruiser Toledo was sent in to provide 8-inch gunfire support and once again Admiral Thackrey was ordered up to take charge. By the 1st of May, as redeployment shipping was beginning to arrive, some 200,000 refugees had clustered in the Inchon area.

          The Chinese breakthrough in the center posed urgent requirements for air support, but the Korean airbase situation remained difficult. In April, in addition to the 5 Marine squadrons in Korea, only 3 of the 18 Air Force groups committed to the conflict could be based in the peninsula; in May runway difficulties at Taegu forced the closing of that field and the return of its F-80s to Japan. Over and above the airbase problem the operations of both carrier and land-based squadrons were complicated by the seasonal bad weather. Fog was reported at sea on 17 days in May, rain and low ceilings were prevalent, and visibility in the combat area was further restricted by smoke haze from brush fires set by the enemy for protection against air attack.

          These circumstances called for the immediate shift of fast carrier operations from interdiction to close support, and for the greatest possible weight of effort. To avoid the loss of a day in four in refueling and rearming, Admiral Ofstie on 24 April began a schedule of daily replenishment. For ten days the force joined the logistic ships in late afternoon to load until midnight, and while this made for a long working day, it also made it possible to keep pace with the high rate of expenditure of aviation gasoline and ordnance.

          To this shift in carrier employment and this intensification of operations there was also added an increase in strength. On 1 May, as Boxer returned from Yokosuka, the retirement of Philippine Sea was delayed, and for three days three carriers were kept on the line. On the same day, as the result of pressure in the west, Bataan’s replenishment period was cut short, her pilots were recalled from leave, and she was sailed from Sasebo for the Yellow Sea. There she joined HMS Glory, recently arrived as relief for Theseus, and there from 2 to 6 May the two ships worked together to strengthen the west coast effort.

          Although close support was for the moment the primary task, the most striking carrier operation of the period was the attack on the Hwachon Dam, which by impounding the waters of the upper Pukhan both provided a barrier to movement and held back water usable for tactical purposes. In January, in the hope of impeding enemy progress, Eighth Army had asked FEAF to hole the dam, but an attack by a couple of B-29s with 6-ton guided bombs had failed of success. On 9 April, as Eighth Army was moving northward, the enemy had turned the trick, and by opening the gates had flooded the Pukhan and decommissioned some bridges. Two days later a small and hastily organized force of cavalrymen and rangers failed in an attempt to capture the dam; on 21 April the KMC Regiment had seized it, only to be ordered back as the Chinese broke through the line on the left. Now at April’s end, as the Chinese lunge expended itself, EUSAK again developed the desire to break the dam, wet down the Communists, and prevent them from using the water as a weapon.

          On the afternoon of 30 April Admiral Ofstie received a photograph of the dam, with a notation requesting that two or more sluice gates be knocked out, and was informed that EUSAK was the requesting agency and wanted it done at once. At 1600 six ADs were flown off with two 2,000-pound GP bombs apiece, accompanied by five Corsairs for flak suppression, and a dive bombing attack was carried out which produced a hole in one gate. A request from EUSAK for another try and a night’s consideration led to a change in ordnance selection: on the next day eight ADs were launched with torpedoes set for surface run, and at 1100 the Skyraiders went in on this now unfamiliar mission. One torpedo was a dud and one erratic, but the remaining six ran true. One flood gate and the lower half of a second were removed, the dam’s western abutment was holed, and the enemy deprived of control of the waters.

          By April’s end the offensive had been contained, and in the first two weeks of May, as Eighth Army probed northward and the enemy prepared for a second try, U.N. aircraft renewed their efforts in interdiction. This interlude brought a temporary expansion of the work of the fast carriers as the result of a request from the Joint Operations Center for help in the interdiction of the western rail lines. In response Rear Admiral George R. Henderson, who had just relieved Admiral Ofstie as CTF 77, advised the JOC that on 11 May he would strike railroad bridges in the triangle which connects Pyongyang, Sunchon, and the transpeninsular line to the east. On the morning of the 11th 32 ADs carrying two 2,000-pound bombs apiece, and accompanied by 32 F4Us for flak suppression and 16 F9Fs for top cover, attacked four of these bridges and dropped spans in three. This success elicited a further request from Fifth Air Force for the destruction of bridges in the rail quadrilateral which links Pyongyang with Sinanju, Kaechon, and Sunchon.

          In reply to this message Admiral Henderson observed that while he would be glad to help out from time to time, existing obligations prevented his assuming any permanent responsibility. But the request for such a "substantial and continuing commitment" of the fast carrier effort brought ComNavFE to his feet, and on 16 May he informed Commander Seventh Fleet that such proposals should pass through appropriate service channels for action by higher authority. But by the time this dispatch was on its way the enemy was on the move again: on the 18th, EUSAK called for maximum effort in close air support, and when interdiction again came to the fore the situation had changed.

          The failure of the Communists’ first attack, and their evident intention to try again, raised the question of the possible employment of new weapons and brought steps to guard against surprise. Where the first five months of war had produced 80 reports of possible submarine contacts, the second five months had brought a mere 16, a change which could be interpreted as either a threat or a promise. In the air, by contrast, there was no question as to the magnitude of the Communist build-up across the Yalu, nor as to the earnestness of the effort to rehabilitate North Korean airfields. Although no air commitment had accompanied the April offensive, the possibility remained, and on the 29th Commander Seventh Fleet again warned of the chance of surprise air or submarine attack.

          For the carrier force, which could operate from beyond MIG range and fight off attacks from other aircraft types available to the enemy, the submarine presented the major hazard, but for the units of Task Force 95 the air question was the serious one. Admiral Smith had alerted his force in April; now on 10 May he advised his ships that the next ten days would be critical with regard to enemy commitment of air strength, credited the Communists with a capability of 300 offensive sorties a day, issued instructions as to procedures to be adopted under attacks of varying weight, and instructed replenishment vessels to avoid anchoring in forward locations.

          In the event, although subsequent evidence indicated that the Chinese had hoped to provide their armies with air support, neither menace developed. FEAF’s attacks on North Korean airfields had kept the rehabilitation effort down, and on 9 May, following reports that 40 fighter planes had been sighted at Sinuiju, on the Korean side of the Yalu, Fifth Air Force sent up 250 Air Force and 56 Marine aircraft to deposit more than 40 tons of bombs on the airfield. In the air, despite promises to his troops, the launching of the second spring drive found the enemy no better off than had the first.

          The weight of the April thrust toward Seoul had led General Van Fleet to bolster his forces in the western lowlands. Contrariwise, while this movement was in progress, the Chinese were shifting eastward to the central mountains, where on the night of 15 May they attacked in strength. On the Soyang River, southeast of the reservoir, the brunt of the attack was again borne by ROK divisions; again these dissolved, and in the exploitation phase the Communists advanced 25 miles down the valley and across into the upper waters of the Hongchon. To the eastward, in the Sorak Mountains, enemy units overran the ROK III Corps and filtered down to the southeast; on the coast the ROK I Corps withdrew south to Kangnung. In the west Chinese divisions crossed the Pukhan below Chunchon, and on the 17th opened a drive down the valley toward the Han.

          As the ground forces struggled to check the attack the supporting arms again stepped up their action. Fifth Air Force increased its effort in close support; on the 17th, after being weathered out for two days, Task Force 77 began another stint of operating by day and replenishing by night; following an appeal from EUSAK for all possible support, Princeton delayed her departure for Yokosuka to permit another period of three-carrier operations. At Inchon, where the enemy was again within range of Toledo’s guns, the drive down the Pukhan brought another redeployment alert, and Admiral Thackrey, who had retained some Scajap LSTs for such a contingency, put in a request for further shipping against the chance that he would have to evacuate the city and the Kumpo peninsula.

          This precaution proved unnecessary. In the center the 2nd Division, which had come a long way since the hard times on the Chongchon River, did what was necessary: although under pressure on three sides it maintained its integrity, held while so instructed, reopened its supply line, and retired on order, with minimum casualties to itself and maximum to the enemy. Three days of violent fighting in the Pukhan Valley saw the Chinese thrust turned back by the 25th Division. In the Sorak Mountains, some 20 miles below the parallel, the enemy was checked at Soksa by the 3rd Division, rushed eastward from Army reserve. By 21 May the Communists had been stopped all along the line. Despite a gain of 30 miles in the eastern mountains, and a considerable penetration in the Pukhan valley, nothing decisive had been accomplished, and the price had been higher than before. On the 23rd Admiral Thackrey began to release shipping from Inchon; on the 25th the evacuation alert was ended, all restrictions on stockpiling ashore were removed, and Toledo was at last relieved of her fire support duties.

Naval gunfire support: A shore party from Toledo at an observation post overlooking the Han. May 1951. (Photo 80-G-432346) Click on the image for additional information and related photographs.

          The Communist spring offensive had brought about a sudden spate of simulated pre-landing operations by units of Task Force 90 and Task Force 95. The first of these, carried out on short notice on 24 April, consisted of a two-hour bombardment of Kosong by St. Paul, Helena, Manchester, and four destroyers. Five days later, on the 29th and 30th, Helena, Manchester, four destroyers, two attack transports and an attack cargo ship made a demonstration in the Kojo area, in the hope of taking pressure off Eighth Army. On the evening of 4 May General Van Fleet asked for another such affair on the 6th and 7th at Kansong; ComNavFE passed the word to Seventh Fleet to do what it could on short notice, and on the 5th Kosong was added as a target at the request of CincFE. On the desired date Helena and four destroyers bombarded as requested; fortuitously, their arrival coincided with a heavy enemy attack, and the bombardment, according to KMAG’s flatteringly redundant description, saved the ROK forces from "complete annihilation." On the 13th Eighth Army called for another demonstration at Kosong on the 18th and 19th; this request was cancelled two days later, but a west coast event already underway continued to its conclusion.

          Feeling, as had his predecessor, that previous demonstrations had been too short and too transparent to produce the maximum reaction, Admiral Scott-Moncrieff planned this with some finesse. Rumors of an impending landing were spread by agents of Leopard Force, a west coast guerrilla organization, and so successfully that aircraft from Glory, flying cover for the minesweepers, reported a large sign near the landing area which read "Welcome, U.N. Army." By 20 May the preliminaries had been completed and Toledo and Commonwealth ships were on hand to provide fire support. In the afternoon a dozen LCVPs, three loaded with Royal Marines and the others empty, were put up on the beach opposite Cho Do, and the Marines made a brief unopposed excursion inland prior to reembarking.

          The popularity of these small demonstrations with Army commanders, and the frequency with which they were requested, led to some study of their actual effectiveness and of measures which might make for greater realism. That the enemy, after the events of the previous autumn, was fully aware of the amphibious capabilities of the United States Navy was unquestionable: information from various sources indicated that special pains were taken to keep track of the movements of the Marine Division. But with the Marines in the line, and given the slow reaction time of the Communist armies, there remained the question of whether much was actually accomplished. Admiral Andrewes had been skeptical; after the operation of 20 May Admiral Scott-Moncrieff remained dubious, feeling that enemy communications were so poor that two or three days might pass before headquarters got the word. EUSAK, on the other hand, estimated that the Inchon feint in February had fixed two Communist divisions, and that the March operation off the Taedong had moved one; following the Cho Do affair in May reports were received of troop movements across the Taedong River into previously undefended areas of Hwanghae Province. Although it seems unlikely that enemy response to any particular demonstration was very impressive, their repetition did serve to emphasize existing possibilities, and to reinforce a real concern about a possible major assault in the Wonsan area. With the passage of time it also brought an increasing concentration of defensive force along the coasts, opposite Cho Do in the west and between Kojo and Hungnam in the east.

          This concentration was heaviest at Wonsan, where day after day the siege continued. Uninterrupted bombardment and frequent air attack had obliged the Communists to commit large numbers of personnel to defense and to repair work and had curtailed enemy transport, but although the railroad had been stopped road traffic was harder to inhibit, and some 500 trucks were thought to pass through nightly. Attempting to take the pressure off, the enemy moved in increasing amounts of artillery and the Wonsan garrison stepped up its shooting; in late April an unsuccessful attempt was made to recapture one of the ROK-held harbor islands. Whether this enemy reaction amounted to a good return on the effort invested was another matter. CTF 95 had earlier advocated emplacing artillery on the harbor islands, but no such step had been taken and the responsibility for dealing with the shore batteries remained entirely upon the ships; additionally, the original offensive purpose of the siege had been undercut by the decision not to attempt a return to Wonsan. The absence of any very clear objective and the size of the commitment proved disturbing to Commander Seventh Fleet, who felt the entire concept of the operation needed some rethinking. Pending such clarification the cruiser previously assigned the Wonsan task unit was withdrawn, and the garrison situation rationalized by the assignment of a Marine officer to Yo Do as commander of the island’s defenses.

          As the enemy’s second offensive slowed, the harassment of his seaward flanks was stepped up, and the Cho Do raid was followed by activity in the east. At Wonsan, following vigorous efforts by enemy artillerists which had damaged a destroyer and bounced a shell off one of the turrets of the recently arrived New Jersey, the rocket ships were sent in for two night bombardments of known gun emplacements. Plunging fire of 7,700 rockets delivered by LSMR 409 and ISMR 412 on 23 and 25 May had impressive results: intelligence agents reported that the enemy was clearing the harbor area of personnel; for three weeks the batteries remained silent. In the north, too, the pressure was maintained: in an interval between bridge bombardments in Kyongsong Man the, destroyer Stickell destroyed a 70-foot motor junk, and followed up by putting a landing party ashore to blow three more with hand grenades.

          Even before the second Chinese push was halted General Van Fleet was preparing his reply. On 18 May he ordered all forces from the Marine Division westward to prepare to attack to the north; next day, with the situation in the eastern mountains improving, he included X Corps in this planned general advance across the parallel. On the 22nd the battle of the Soyang River entered its offensive phase as the Marines and the 2nd Division attacked to the northeast against vigorous resistance. In the west, at the same time, I Corps moved steadily northward toward the so-called Iron Triangle, the important and heavily defended area bounded by the towns of Chorwon, Kumwha, and Pyonggang. Since seizure of the Iron Triangle would open the corridor to Wonsan, this movement held great possibilities.

          The advance up the Soyang valley toward Inje threatened to cut off the Chinese in the Sorak Mountain salient, and opened the possibility of a thrust through the mountains to Kansong which would trap the enemy forces on the coastal strip. To provide logistic support for such a move some Scajap LSTs, released from Inchon, were assigned to meet the advance at Kansong and establish an advanced supply base. But the threat at Inje made the operation unnecessary, the enemy pulled back, and on 29 May, with minesweeping completed and gunfire about to begin, ROK forces regained control of the Kansong area. By the end of the month the armies of the U.N. were back at the Hwachon Reservoir, and in firm possession of the line from which they had been dislodged by the attacks of April.

          The two Communist thrusts and the U.N. counteroffensive had brought the enemy out into the open, and had provided profitable targets for air attack. The response to this opportunity had been vigorous: Fifth Air Force had stepped up its sorties in support of Eighth Army; Task Force 77 had shifted to continuous operations and daily replenishment; in times of crisis all three fast carriers and both light carriers had been put on the line. The statistical results were impressive: the Air Force claimed 21,536 enemy personnel "destroyed" in April and May; Task Force 77 aircraft claimed 1,400 killed on 29 May; on 4 June, following attacks by carrier planes, the advancing ground forces counted more than 1,000 dead.

          Whether all this effort, indubitably severe in its effects on the enemy, amounted to efficient close air support was another matter. In his report for this period Admiral Martin observed that while three fast carriers had been employed at Army request, the calls for close support had never exceeded the capacity of two, the controllers had once again been swamped, and much ordnance had been dumped. Nor were the Marines more satisfied. In the later phases of the battle of the Soyang River the division, advancing at a rate of three miles a day against continuing stiff resistance, wanted and needed support from the air, and on two days requested all available aircraft. But advance requests, submitted on the previous day conformably with Air Force practice, were only about half-fulfilled. And while the use of special emergency requests produced a sortie total approximating that originally called for, processing delays were such that time from request to receipt of aircraft averaged 95 minutes.

          Such delays, varying unpredictably from one to two hours, have obvious effects on the momentum of attack and on the health of the attackers. To those accustomed to getting strikes in 10 to 20 minutes from aircraft orbiting on station, they were unacceptable, and led to loss of confidence in air support on the part of front line commanders. On 31 May the division commander made the inadequacies of the situation the subject of an official report to X Corps, and such was the feeling within the division as to bring an investigation by the Commanding General, Fleet Marine Force Pacific, once again in Korea on an inspection tour. After working through the numerous and sometimes contradictory allegations, and attempting to separate fact from fancy, General Shepherd concluded that the JOC processing time, the remoteness of airfields from the front lines, the struggle between Mosquito aircraft and ground parties for control of strikes, and the unwieldy nature of the Army-Air Force system, which forced communications to parallel the chain of command all the way to the top and back again, added up to excessive and unacceptable delay. In March he had raised the subject with Fifth Air Force, but to little purpose; now he went to the top, and on 24 May discussed the close support question with CincFE. With General Ridgway’s view that it was improper for Marine air to support the Marine Division exclusively, General Shepherd concurred; for this problem, inevitable when a division with a private air force specializing in troop support was operating in company with air-starved Army units, no other answer was possible. But the basic difficulty was less the identity of the aircraft than the nature of the system, with all its built-in delays.

          In June, as the Marine Division continued on the offensive east of the Hwachon Reservoir, two changes were made. Permission was secured from Fifth Air Force to keep four Marine aircraft on alert at an advanced airstrip, and to notify them of requirements by messages paralleling those to JOC. But direct communication with the airfield remained prohibited, the policy of scrambling and reporting was not permitted, and takeoff still had to await word from JOC. At the same time, in view of the radical discounting of routine requests in May, the Marines adopted a policy of submitting special requests only. But this proved self-defeating, as the resultant saturation of JOC communications facilities tended to offset other efforts to diminish delay time. This indeed was decreased in June to an average of 81 minutes, but the percentage of requests fulfilled dropped from 95 to 74 in good weather, and to 65 for the month as a whole, and nobody was much the happier.