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Advance to the 38th Parallel:
The Marines in Operation Ripper

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Operation Ripper

Author - Lynn Montross
Reprinted from the March 1952 issue of The Marine Corps Gazette
Reprinted with permission to The Korean War Educator.

An operation per month—this seemed to be the pace of the 1st Mar Div as part of the US Eighth Army in the first quarter of 1951. January and early February had dated the guerrilla hunt in the Pohang-Andong sector of southeast Korea. Then the Leathernecks moved up to the central front to spearhead the advance of X Corps from 21 February to 4 March in Operation Killer. [These operations were the subjects of articles appearing in the last two issues of the Marine Corps Gazette. Previous Marine operations in Korea have been described in consecutive issues of 1951 from June to December.] Three days after the drive ended, the 1st Mar Div was scheduled to jump off again on D-day of Operation Ripper.

This attack was actually a continuation of Killer, with only a brief breathing spell for bringing up supplies and shuffling units on a front extending across the peninsula. The new drive, in fact, was the fifth consecutive offensive to be planned in rapid succession since 15 January by LtGen Matthew B. Ridgway, CG Eighth Army.

When he assumed the command on 26 December 1950, the Chinese Communist forces were poised for their second great counteroffensive in two months. It struck the Eighth Army in the paralyzing cold of New Year’s Eve, and the collapse of major ROK units made a general withdrawal necessary to guard against envelopment.

Seoul and Inchon were abandoned to the enemy as the retreat continued through the first week of January 1951. These new losses of ground meant that the United Nations front was about 200 miles south of the line held late in November before the first CCF counteroffensive.

Nevertheless, the Eighth Army had put up a stout fight against the “human sea” tactics of a numerically superior enemy. There was no sense of failure, for all ranks realized that ground had been sacrificed rather than personnel. Morale and fighting spirit remained so keen that Gen Ridgway was able to launch his first offensive barely a week after the retreat ended. It was a reconnaissance-in-force conducted by a task force spearheaded by a reinforced RCT. Two other drives followed in rapid-fire order, each larger and more ambitious than its forerunner, until most of the UN combat forces were involved along the entire front.

This was the situation in the middle of February when the Eighth Army commander planned his fourth offensive, Operation Killer, while resisting a CCF counter-attack. All four drives had one thing in common. However much they might differ with respect to units and objectives, all were formulated in accordance with the basic directives announced by Gen Ridgway when he assumed command:

“Inflicting maximum casualties while sustaining minimum losses; maintenance intact of all major units; strict observance of lateral security.”

The Marines had a word for it—“buttoning up” the offensive. But even though the primary objective of Operation Killer was the destruction of the enemy rather than gaining ground, Gen Ridgway attached great importance to control of the hill mass of the central front. For it was believed, on a basis of G-2 reports, that this corridor was a likely avenue of approach for the next great CCF counteroffensive.

The 1st Mar Div therefore, had the mission of attacking northward from Wonju to Hoengsong in coordination with other IX Corps units while I Corps advanced on the left and X Corps and the ROK Army on the right. From 21 February to 4 March the Leathernecks fought their way forward methodically, paying strict attention to integrity of units and lateral security. The advance was in formation of “two up and one back”—two regiments in assault, with a battalion and regiment constituting the reserve.

Operation Killer was not the most dramatic fight of Marine Corps history. But it was good “war according to the book” which paid off in results. All objectives were taken on schedule with precision of maneuver and economy of means. At the finish, on 4 March, the 1st Mar Div occupied hills just north of Hoengsong after total losses amounting to less than a fourth of the estimated 1,868 casualties inflicted on the enemy.

The following day MajGen Oliver P. Smith was relieved of the temporary command of IX Corps he had been assigned when MajGen Bryant E. Moore died on 24 February from a heart attack. Gen Smith resumed his command of the 1st Mar Div after the arrival of MajGen William H. Hoge, USA, at IX Corps headquarters.

The success of Operation Killer had already led to Eighth Army plans, actuated by Gen Ridgway on 1 March, for a fifth offensive all along the UN front. The primary mission of Operation Ripper was to inflict as much destruction as possible, and by means of constant pressure to keep the enemy off balance in his build-up for another counteroffensive. A secondary purpose was to outflank Seoul and the area between that city and the Imjin River, thus compelling the enemy to choose between default and a defense on unfavorable terms.

The basic plan called for the drive of IX and X Corps toward the 38th parallel on the central front. Protection was to be given on the left flank by I Corps in the area south and east of Seoul, while the ROK Army maintained lateral security on the right with a partial northward advance.

Again, the rugged terrain of the central front was certain to multiply the difficulties of attack. Logistics were reduced to their most primitive terms in an area of many crags and few roads. The enemy had not neglected such defensive advantages in Operation Killer, and the Marines found themselves up against a succession of hills bristling with log bunkers. Little attempt was made to hold these positions in force, and at night the Chinese usually fell back to the next height for more delaying tactics. Apparently the enemy was contenting himself with an elastic defense while bringing up supplies and reinforcements for his next counteroffensive.

On the eve of Operation Ripper the UN forces held a line extending from Inchon to the south of Seoul, then across the peninsula by way of Hoengsong, to the east coast in the vicinity of Chumunjin. Gen Ridgway’s new offensive contemplated an advance by successive phase lines to drive a salient into CCF territory.

The X Corps scheme of maneuver called for the 1st Mar Div to maintain lateral contact with the 1st Cav Div on the left, and the 2d Inf Div on the right. Hongchon and Chunchon, two of the main objectives of Operation Ripper, lay directly in the path of IX Corps. Both were important communications hubs, and G-2 reports indicated that the enemy might make a determined stand. It was even considered possible that CCF withdrawals in Operation Killer had been planned to screen a counterattack to be launched from the Hongchon area.

The first phase line in the IX Corps zone was Albany, representing about half the distance from the line of departure to Hongchon and the line Baker. Distance in this area, however, was conditioned by terrain; and it was a natural fortress of wooded hills and swift streams which confronted the 1st Mar Div. Highways were conspicuous by their absence, and extensive maintenance would be required to utilize the Hoengsong-Hongchon road as a MSR. So few and poor were the secondary roads that it would sometimes prove necessary for vehicles to detour along the rocky stream beds.

The last offensive had not developed major or prolonged resistance at any point. Yet that possibility, as well as a resumption of delaying tactics, had to be anticipated by Marine planners of Operation Ripper. At least the enemy units were old acquaintances, for the Leathernecks still faced the 66th CCF Corps, commanded by Gen Show Shiu Kwai. The 196th Div was on the left and the 197th on the right, with the 198th in reserve near Hongchon. These units were believed to comprise about 24,000 men. G-2 reports told a story of low morale. Many of the troops were former Chinese Nationalists impressed into Communist service, and supplies of food and clothing had been meager since crossing the 38th parallel.

The Leathernecks did not need the map to locate phase line Albany. It was indicated by Oum Mountain, a stark 930-meter peak about five and a half miles from the line of departure. The Hoengsong-Hongchon road, winding through Kunsamma Pass to the left, paralleled the boundary between the two Marine assault regiments, RCT-7 on the left and RCT-1 on the right. They were to attack in line abreast, using all three battalions when the terrain permitted, while RCT-5 continued its patrolling activities in division reserve.

Operation Ripper began according to schedule all along the Eighth Army front on the morning of 7 March. The two Marine regiments encountered light resistance the first day, consisting of small arms and mortar fire. Again the enemy seemed to be up to his old tricks, putting up a limited defense with units ranging from platoon to company strength.

Fairly typical of the first day’s operations was the experience of the Div Recon Co, which conducted a screening patrol from 0800 to 1500 on the right flank of RCT-1. Bursts of small arms and automatic fire were received from Chinese dug in on a hill, but they departed in such haste as to leave several cases of grenades behind. As the Marines proceeded, they were greeted by 10 or 12 rounds from a 60mm mortar in addition to small arms and automatic fire. After another interval, the enemy opened up with artillery—a single round of white phosphorus, followed by four or five harmless rounds of HE. Then the company was allowed to complete its mission without further trouble.

The effectiveness of CCF resistance on D-day may be judged from the total of seven wounded, representing 1st Mar Div losses, with all objectives occupied on schedule. This does not mean, of course, that the Leathernecks found easy going. The terrain itself was enough to demand the utmost in endurance from units maintaining strict lateral contact and mopping up all resistance before proceeding.

On the evening of D-plus-two, after total gains of about two and a half miles, the two Marine regiments were halted by Corps orders to wait for the 2d Inf Div to advance on the right. Stiffer resistance had slowed up the Army assault troops, and Marine operations of the next two days were limited to patrolling.

The 1st Mar Div jumped off again at 0800 on the 11th toward line Albany, meeting the same light and scattered opposition. A division G-2 analysis concluded that these “hit and run tactics” were probably intended to wear down UN forces until the enemy could launch his long expected counteroffensive with more heavily armed troops training in Manchuria.

At any rate, the two Marine regiments slugged their way forward methodically until most of the units reached line Albany on 12 March. The enemy withdrew from many positions without resistance, yet a 3/1 patrol had a hot fire fight with two CCF platoons on Hill 549. After destroying five log bunkers with grenades, the patrol called on the 11th Marines for artillery fires, which finished the job.

The first phase of Operation Ripper ended for the Marines on 13 March, when line Albany was completely occupied. And though the terrain discouraged maneuver, the tanks of the 1st Tank Bn knocked out CCF positions on several occasions with 90mm fires.

Again, as in Operation Killer, Marine air operations were directed by the Fifth Air Force. Thus the planes of the 1st Mar Air Wing supported other Eighth Army units as well as the 1st Mar Div. Two groups participated during Operation Ripper. MAG-12, flying from Pusan, included VMFs 214, 312, and 323 as well as VMF(N)-513. Based at Pohang were VMFs 212 and 311 of MAG-33.

At the front the situation was aggravated by spring thaws and rains which turned roads into bogs. The difficulties might have grown more serious except for the new Civil Transport Corps.

This organization of porters was made up of friendly Koreans of the ROK National Guard who lacked the training for military duties. There was no lack of willing indigenous labor, for the auxiliaries received pay as well as rations and clothing. Formed into companies they were equipped with the wooden “A-frames”—so-called because of their shape—used in Korea as a pack harness.

The Civil Transport Corps soon proved to be a boon for the Eighth Army as well as the Korean porters, each of whom could carry from 60 to 75 pounds of supplies over terrain too rugged for motor vehicles or even carts. Several hundred were attached to each Marine regiment during Operation Ripper, and many of them became devoted to their own Leatherneck outfit. When transferred to some strange unit, they were capable of showing their loyalty by returning after a weary hike across the mountains.

The highly-mechanized Eighth Army was thus reduced at times to the world’s oldest form of transport as Operation Ripper went into its second phase on 14 March. Gen Ridgway had recently advanced his tactical CP from Suwon to Yoju as the front moved northward. Here he conferred with Gen Hoge as to the possibilities of using maneuver instead of frontal assault in the forthcoming attack on Hongchon.

This important IX Corps objective was believed to be the supply center for the CCF 39th and 40th Corps, which had conducted the enemy’s counterattacks of February. Gen Ridgway asked the new IX Corps commander to prepare a plan for working around the flanks in a double envelopment. Such methods had been used successfully in recent small-unit operations, and IX Corps had a prospect of bagging large numbers of enemy troops.

Gen Hoge acted promptly and a IX Corps operation directive of the 13th named the 1st Cav Div and 1st Mar Div for the Hongchon envelopment. The next morning, as IX and X Corps jumped off from line Albany toward line Buffalo, the 1st Mar Div retained the same formation—RCT-7 on the left and RCT-1 on the right, with RCT-5 in reserve. Again the division maintained lateral contact with the 1st Cav Div to the west and the 2d Inf Div to the east.

Flash floods had recently added to the troubles of the Leathernecks, increasing the difficulties of road maintenance and making it a problem to find a dry bivouac area. The enemy put up less resistance than the weather when the two assault regiments renewed the attack at 0800 on the 14th. RCT-7 occupied its objectives without once calling for air or artillery support, and RCT-1 received only sniper fire. Division casualties for the day amounted to a total of six men wounded.

Reports of light opposition met by other IX and X Corps units were overshadowed by the news from Seoul—a patrol of the 1st ROK Div had entered the former ROK capital on the 14th to find it undefended. One of the objectives of Operation Ripper, it will be recalled, was to outflank the area, thus forcing the Chinese to choose between withdrawal and fighting at a disadvantage. The enemy had made his decision, and I Corps units took over a devastated city with some 200,000 civilians still existing in the ruins. Dead power lines dangled over buildings pounded to rubble, and even such landmarks as the enormous brass-studded red gates of the embassy compound had been obliterated.

It was the fourth time that Seoul had changed hands in nine months of war. Air reconnaissance established that the enemy had pulled back about 15 miles to entrenched positions in the Uijongbu area. Gen Ridgway enlarged the mission of I Corps accordingly by directing a new advance on the left of IX Corps.

Evidences of CCF withdrawals only added to the conviction of Eighth Army staff officers that a great counteroffensive was in the making. No less than 4,630 enemy vehicles had been sighted by Air Force planes from 8 to 12 March—the largest number to be reported in a like period since Gen Ridgway began his offensives. Few of these resupply and reinforcements efforts were observed in the eastern sectors of the UN front. One concentration was directed toward the northern approach route to Seoul, and on the central front the vehicles appeared to be converging toward Chunchon.

Enemy delaying tactics showed an increasing reliance on road mines. Artillery shells were buried for the purpose, and the Chinese also packed explosives in wooden or pottery containers to avoid detection. Sudden changes of spring weather made for freakish variations which baffled the engineers. Thus a tank might pass over a frozen road in the morning without harm, while a jeep would be blown sky-high that afternoon if a rain or thaw softened the earth and made the mine more sensitive.

The enemy was equally unpredictable. On 14 March the Marines’ advance of two to three miles had scarcely been opposed. But on the 15th, while driving on toward line Baker, the two assault regiments ran suddenly into their stiffest resistance of Operation Ripper.

Three heights had been fortified by the Chinese to defend Hongchon from the east and southeast—Hill 356 in the zone of RCT-7, and Hills 246 and 428 in the path of RCT-1. The slopes were studded with pill boxes and log bunkers giving overhead protection, while the camouflaged mortar emplacements were located to provide mutually supporting fields of fire.

Field reports are a little vague as to what happened to the Hongchon envelopment. Apparently, however, the plans were changed at the last minute because of intelligence that the enemy had pulled out of the heavily bombed town. At any rate, the 1st Bn of RCT-7 entered Hongchon without a fight on the 15th, then passed through constant artillery fire and enemy-defended high ground overlooking the town from the northwest. The real struggle came when the other two battalions attacked Hill 356. Chinese mortar fire was so well aimed that three out of six 81mm mortars were knocked out in the 3d Bn mortar platoon. The attacking Leathernecks were also pounded with artillery fire, and at dusk they had barely won a foothold while the enemy still clung to his main positions.

An intricate maneuver featured the assault of RCT-1 on the two hills in its zone. The 2d Bn was ordered to swing from the regimental right flank, where no enemy were encountered, to the extreme left. In order to execute the shift, the battalion had to circle to the rear, then move by truck up the MSR and through the zone of RCT-7 to the village of Yangjimal. Dismounting there at 0925, the men began a difficult march across broken country toward Hill 246. At 1230, after receiving CCF mortar fire, the column deployed and attacked in conjunction with the assault of the 3d Bn on Hill 428.

The enemy, defending heavy log bunkers, sometimes held his small arms and automatic fire until the Leathernecks came within 100 feet. At times the fighting was at such close quarters that no supporting weapons except 60mm mortars could be used, and the terrain was too rough for the approach of tanks.

The 2d Bn secured Hill 246 by 1700 and dug in for the night. Hill 428 was a harder nut to crack, and the 3d Bn withdrew from the forward slope to resume the assault in the morning. During the night the enemy withdrew, however, and RCT-1 advanced to line Baker without a fight the next day.

Another hard action awaited RCT-7 on the 16th, when the 1st Bn moved up to line Baker. The Chinese resisted on Hill 399 so stubbornly that the Marines had to drive them out of their bunkers with bayonets and grenades. Meanwhile the wrecked town of Hongchon was being secured as Marine engineers began the task of clearing the airstrip.

Recent intelligence reports indicated that the CCF 66th Corps, opponents of the Marines since the outset of Operation Killer, was being relieved after frightful personnel losses. Prisoners taken on 17 March identified their unit as the CCF 39th Corps and declared that the 66th was being withdrawn to North Korea for recuperation.

Corps orders were received for the 1st Mar Div to attack on the 17th from line Baker to Buffalo. The division plan of maneuver called for RCT-5 to pass through and relieve RCT-7 while RCT-1 continued to advance on the right.

All the way to the objective the assault troops met such light resistance that another large-scale CCF withdrawal seemed in progress. By the 20th, five of the six Marine battalions had reached line Buffalo after encountering only sniper fire and a few mortar shells. Enemy opposition was reserved for the 2d Bn of RCT-1, which had a lively fight to take Hill 330, located on the objective line itself.

No enemy had been sighted by RCT-1 until the 19th, when Fox Co ran into small arms bursts from the nose of this long, narrow ridge running north and south.  Unusually heavy log bunkers gave the Chinese good protection, and it was lucky for the Leathernecks that the terrain permitted tank maneuver.  While Fox Co organized for the assault, a platoon from Baker Co of the 1st Tank Bn demonstrated how valuable this support could be.  Sweeping up the valley to the left of the ridge, the tanks neutralized CCF positions with their shells.  Under cover of this flanking fire, Fox Co was able to work its way up to the top without losses.

The battalion dug in that night on Hill 330.  Three probing attacks were received before daybreak from an enemy apparently trying to withdraw without getting his tail feathers singed.  Later it was learned that these efforts were made to cover the relief of CCF 39th Corps units by North Koreans of the V NK Corps.

Two Marine patrols, working forward along the ridge, ran into so much fire on the 20th that they were pulled back.  The final assault was put off until the next day, when it demonstrated the terrific wallop packed by coordinated Marine arms.  An artillery barrage preceded the infantry jump-off, and an air strike also pounded enemy positions.  Then, as the infantry attacked along the ridge line, tanks moved forward on each side to fire on every bunker showing signs of life.

Panic seized the North Koreans, who sought an escape down the east slope, only to be wiped out by the tanks on that side.  By 1315 the Leathernecks had overrun the enemy's main line of resistance without a single casualty.  Here they were astounded by the spectacle of an NK officer buried alive by a shell burst, with only his hand waving feebly when the Marines arrived on the scene to dig him up unhurt.

As Easy Co continued along the ridge line, two men were wounded late in the afternoon.  This was the extent of 2d Bn casualties for the day, and the total for three days of fighting added up to one killed and 12 wounded.  Enemy losses for the same period were estimated at 213 killed, of whom 53 were counted.  The number of wounded could not be ascertained, for the NK remnants abandoned Hill 318 that night and retired northward.

This fight delayed the RCT-1 advance when the Eighth Army jumped off on 20 March from line Buffalo to lines Cairo and the final objective.  The 1st Mar Div was now able to operate on a front of three regiments, having been reinforced by the 1st Korean Marine Corps Regt.  Before the Inchon landing, this regiment had been organized and trained by officers and NCOs from the US Marine Corps.  Made up entirely of volunteers, the unit served with distinction in the Inchon-Seoul operation and in northeast Korea after the Wonsan landing.

The aggressive KMC Regt showed what could be accomplished by ROK troops with the proper training and equipment.  The spirit of the outfit shines forth from instructions written in his own English by the S-3, Lt Kim Sik Tong, in the periodic operation report for 24 March:

"The KMC ideal is to complete the mission, regardless of receiving strong enemy resistance, with endurance and strong united power, and always bearing in one's mind the distinction between honor and dishonor."

The regiment lived up to this high ideal in its attack on Hill 975--the hardest fight of the 1stMarDiv advance.  Before RCT-1 secured Hill 381, the KMC Regt and RCT-5 jumped off on the 20th.  The latter reached line Cairo the next evening, having met little resistance, and on the left the 1st KMC Bn pulled up alongside the next morning.  RCT-1 reached the final objective on the 23d after driving NK troops out of prepared positions.  The 2d KMC Bn also had to slug its way forward, but it was the 3d Bn which had the struggle.  The assault on the key enemy position lasted through the day on the 23d, and not until 0300 the next morning was Lt. Kim Sik Tong able to record that "our indominatable [sic] spirit which finally recaptured Hill 975 after hand and hand combat...will brilliantly decorate our KMC history."

Although the 1stMarDiv had secured its objective by the 24th, IX Corps ordered a further advance to a new Cairo line on the 26th.  This was an eastward extension of the old line to the boundary between IX and X Corps.  There was no need for RCT-5 to advance, and RCT-1 and the KMC Regt moved up to the new line on schedule without being opposed.

This was actually the finish of Operation Ripper according to its original conception.  All of its main objectives had been taken by Eighth Army units who stood just below the 38th parallel.  Average gains of about 50 kilometers had been made in three weeks, while "tremendous" casualties were being inflicted on the enemy.

Despite these successes, all signs pointed to the fact that the enemy had been fighting delaying actions while building up for a great counteroffensive.  On 27 March a 1stMarDiv G-2 report contained translated excerpts from a speech by Gen Peng Teh Huai, reported to be the commander in chief of CCF and NK forces in Korea:

"We are forced to begin the 4th Battle Phase of military operations in Korea.  This operation begins under unfavorable conditions because we are compelled to face it without a transitional period of sufficient preparation."

Gen Huai added that the CCF tactics

"will be very exacting for us, but through our painful efforts we can win.  The enemy had become pessimistic and disappointed, while we are the winner.  Let us go on until we liberate the whole of Korea!  However, we need much material and ammunition."

The certainty of a new CCF counterstroke caused Gen Ridgway to decide on maintaining the momentum of Operation Ripper.  Although most of its aims were achieved, the mission of destroying enemy had been only partially completed.  Rugged terrain and muddy roads had slowed up the mechanized Eighth Army in many instances, enabling the enemy to defend briefly with small units and withdraw to prepared positions.

Gen Ridgway's problem was two-fold.  He wished to continue his forward movement, yet he had to be ready to stand on the defensive when the time came.  As a dual solution, he published on 29 March a plan for a new Eighth Army advance to a line further north.  Mountainous and almost roadless terrain on the east flank, the Hwachon Reservoir in the center, and 23 kilometers of tidewater on the west flank made it possible to prepare a strong defense in dept on this new line.

New names were to be applied every few days to various phases of the new UN offensive, but it was in reality an extension of Operation Ripper, just as the latter had been a continuation of Killer.  Actually the Eighth Army had been driving steadily forward, with only brief interludes, since 21 February.  And as the troops jumped off again on 2 April, Gen Ridgway emphasized once more to commanders his familiar three basic tenets:  "Coordination, maximum punishment, and maintenance intact of major units."

This was one of Gen Ridgway's last operations as CG Eighth Army.  For on 14 April he was appointed commander in chief by President Truman to succeed Gen Douglas A. MacArthur, and LtGen James A. VanFleet assumed command of the Eighth Army.

On 1 April the 1st Mar Div reverted to Corps reserve.  The Marines were also directed by IX Corps to move to an assembly line south of Chunchon, which had been hastily abandoned late in March before an Eighth Army airborne assault could be launched to trap enemy troops.  The 1st Mar Div was to be relieved by X Corps units and be prepared in turn to relieve the 1st Cav Div.  Meanwhile, RCT-7 was to be attached to that Army division on 1 April.

Further IX Corps instructions the next day directed that RCT-1 go into Corps reserve at Hongchon while other units participated in the advance to line Ready.  On the 3d, the KMC Regt and RCT-5 attacked toward this objective and secured it the following day.  There the relief by X Corps units took place, being completed on 5 April.

RCT-7 was ordered by the 1st Cav Div to take over a sector on the west of the division zone after relieving elements of the 6th ROK Div and 8th Cav Regt.  On 2 April the attack jumped off from line Dover, north of Chunchon.  Three regiments in line, from left to right, the 7th Mar, 8th Cav, and 7th Cav, advanced for three days without opposition.  And on 4 April the Leathernecks were among the first UN troops to cross the 38th parallel.

It may have occurred to them that never before had a line of latitude acquired so much worldwide renown.  The 38th parallel first came to international notice after the collapse of Japan at the finish of WWII.  Originally it was designated by agreement as the boundary between Soviet and US zones of military occupation in Korea, but the Russians soon made it into a frontier between militant Communism and Democracy.

The historical lesson may have been lost on the Marines, for it was at this point that they ran into heavy opposition.  After a brisk fire fight the two forward battalions dug in for the night.  They resumed the attack on the 5th, advancing more than a mile.  But it took another effort the next morning to reach the 1st Cav Div's objective, and in the process the men received about 50 rounds of enemy artillery fire.

successes of the first few days in April led Gen Ridgway to publish on the 6th another operation plan designating new objectives to the northward.  The purpose of advancing to a new phase line was to push beyond the Hwachon Reservoir and seize the approaches to the "Iron Triangle."  This strategic area, bounded by Kumhwa, Chorwon, and Pyongyang is one of the few pieces of comparatively level real estate in all Korea.  Because of its network of good roads, the broad valley had been developed by the enemy as a supply and troop concentration center.

On 8 April, in preparation for the renewed effort, the 1stMarDiv (less RCT-1) was directed by Corps to relieve the 1st Cav Div and be prepared to attack to line Quantico and the new phase line beyond the Hwachon Reservoir.  RCT-7 was to revert to division control on completion of this relief.

Although the 1st Cav Div had not secured all its objectives, the 1stMarDiv took over on the 9th and 10th.  From left to right the Marine regiments were RCT-7, RCT-5, and the 1st KMC Regt.

At this time the 7th Cav Regt was still attempting in the Hwachon Dam area to complete its seizure of assigned objectives before being relieved.  The enemy had opened the flood gates on the 9th, causing the Pukhan River to riser four feet and depriving IX Corps for a few days of two floating bridges.  An attack that day by the 7th Cav Regt failed to dislodge the enemy from the high ground south of the dam, and another assault failed on the 10th.  A third attempt was made on the 11th, with the 4th Ranger Co assisting by crossing the lake above the dam in assault boats.  Again the enemy positions were found too strong, and the Army elements were relieved on the 12th by the 1st KMC Regt as the 1stMarDiv assumed responsibility for the sector.

In view of commitments for the advance north of the Hwachon Reservoir, it was decided to postpone operations in the Hwachon Dam area until a stronger force could be assigned.  During the following week the 1stMarDiv patrolled aggressively as positions were consolidate.  Some hot fire fights took place in these operations, with the enemy using artillery on several occasions.

RCT-1 was permitted on 14 April to move up to the Chunchon area, though the regiment did not revert from Corps to division reserve until two days later.  Boundary changes between the 1stMarDiv and 6th ROK Div on the left extended the Marine zone to the west, and on the 19th the division CP was advanced to Sapyong-ni, just south of the 38th parallel.

A heavy pall of smoke hung over the front these days as the enemy burned green wood to screen his preparations for a counterstroke.  The time was believed to be near on 21 April as the 1stMarDiv attacked at 0700.  The 5th and 7th Marines pushed northward from 5,000 to 9,000 meters without meeting any opposition, and the 1st KMC Regt occupied its objectives on schedule.  Division casualties for the day consisted of one man wounded.

Similarly, gains by other IX Corps units pointed to enemy withdrawals.  When the advance was renewed at dawn, the 1st Mar Div secured line Quantico against light resistance.  RCT-5 seized the high ground dominating the Siphung-ni road, and on the left RCT-7 advanced about 5,000 yards.  After forcing a crossing of the Pukhan River, the KMC Regt completed the seizure of the Hwachon Dam as the Div Recon Co sent patrols into the battered town of Hwachon.

This was the moment chosen by the enemy for his long expected counterstroke.  The blow fell at 2215 on the night of 22 April in the sector of the Marines, who were informed that dangerous CCF penetrations had been made to their left in the zone of the 6th ROK Div.  Before daybreak the withdrawal of ROK units had exposed the Leathernecks to envelopment, and elements of RCT-1 were brought up from reserve to protect the left flank.  Division orders suspended the attack, and all units were directed to consolidate positions for defense.


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