The Sea War in Korea 1950 – 1953

Author

Murray, D.S., Rear Admiral

Subjects

None noted

Tags

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RAN Ships

None noted.

Publication

June 1976 edition of the Naval Historical Review (all rights reserved)

Amphibious Assault at Inchon.

While the US and South Koreans were hanging on grimly at the south-east end of Korea, plans were being made in Tokyo for a landing at Inchon. Sometimes called the most striking example of the effectiveness of an amphibious operation, the credit is given to General Macarthur for conceiving it and then fighting it through the Joint Chiefs of Staff in Washington before final approval was given by the Secretary of Defence.

Macarthur said, ‘The history of war proves that nine times out of ten an army has been destroyed because its supply lines have been severed. A deep envelopment, based upon surprise, which severs the enemy supply lines is, and always has been, the most decisive manoeuvre of war.‘

It is understandable that the Navy said, ‘The Inchon operation is not impossible.‘ The tides of Inchon have a range of between 23 and 33 feet – the worst in the Far East; except for a slack water period of about 50 minutes there is usually a five knot ebb or flood stream running. The approach channel to Inchon, poetically called Flying Fish Channel, is narrow and difficult for even daylight passage; and then there were no navigation lights and there was the possibility of enemy gun fire and mines. If a ship ran aground in the channel approaches the ships ahead would be trapped, particularly at low water. At least 29 feet of water was required to ensure that the LSTs could reach the selected landing beaches and there were only four days a month when such high tides were available. The first opportunity was September 15th, give or take a day or two. Other hazards were the location of the city, which had protecting sea walls, and the position of the island of Wolmi Do. This island lies in the channel 800 yards off Inchon and was connected to it by a narrow causeway. The island was suspected to be heavily armed. The US plan of operations included:

• A battalion of marines to land in assault on Wolmi Do at 0630 to seize the island prior to the main landings;
• After the Wolmi Do landing, further landings to be made on Red, Yellow and Blue beaches by the First Marine Division on the afternoon high tide at about 1700/15 September.
• The beachhead to be extended rapidly to seize Kimpo Airfield and the Han River line west of Seoul. The advance then to be continued to seize the city of Seoul.
• Bombardment and fire support, to be provided by cruisers and destroyers.
• Air cover strikes and close support to be provided by carrier aircraft.

The whole planning of this vast and complex operation was completed in 23 days – supposedly a record. The principal forces were:

• The attack force which included the First Marine Division;
• The landing forces (10th Army Group);
• The Patrol and Reconnaissance Forces;
• The blockade and covering forces (HMS Triumph (under F02FES)) 1 light fleet carrier, 1 cruiser, 8 destroyers including HMA Ships Bataan and Warramunga;
• The fast carrier forces (Task Force 77) – 3 attack carriers, 2 cruisers, 14 destroyers and other smaller groups.

The neutralization of Wolmi Do commenced on 10th September. Marine aircraft dropped 95 tanks of napalm, which burnt out 39 of the 44 buildings in the warehouse area. This was followed by two days of air strikes to soften the island’s defences. On 13th of September a pre-invasion bombardment of Wolmi Do was carried out by four cruisers and six destroyers. Three destroyers were hit by the island guns but none seriously. The advance attack force landed on Wolmi Do early on the 15th as planned and captured the island in 42 minutes. The defenders lost 120 dead, the marines’ casualties amounted to 20 wounded.

That evening the actual invasion of Inchon began at 1730. The major landing tasks were carried out by 8 LSTs, some of whom had only been in commission about 17 days and some who were experiencing their first beaching; they had had no training or practice time. 23 waves of LVTs landed with the 8 LSTs on Red Beach while on Blue Beach 15 waves of LCVPS took the marines ashore. Green and Yellow Beaches, which were on Wolmi Do and the tidal basin of the inner harbour respectively, were logistic beaches and not used until D+l. There was only light resistance from a few tanks and 2 or 3 hundred enemy troops. Assisted by close air support and accurate strikes from the carriers the landing force moved quickly and Seoul, the capital, was retaken on September 25th.

It was a great victory and showed once again the value of the marines and the doctrine and technique of amphibious warfare, together with the flexibility of naval air power. Of course it should be remembered that at Inchon there was no submarine opposition, very few mines, no surface naval opposition, no enemy air opposition and the actual ground opposition to the landing was light.

Within a few days of the capture of Seoul the North Korean Army was in full retreat from its positions around Pusan. Entire enemy divisions completely disintegrated and were spread over the Korean countryside in disorganised units. With their lines of communication and supply completely severed many enemy troops were trapped in the south-west corner. Tanks, mortars, artillery and other arms and equipment were abandoned in their haste to escape.

By the end of September 23,600 North Korean prisoners had been taken by the UN Forces; in addition the Inchon-Seoul operations cost North Korea 16,000 casualties and prisoners. The remnants of the North Korean Army, who only a fortnight previously had stood poised to take Pusan, were now back over the 38th parallel desperately trying to defend their own territory.

The application of sea power, which allowed the landing at Inchon, has seldom produced results so swift and startling.

On 30th September General Macarthur broadcast a demand to the Premier and C-in-C of North Korea for the surrender of his forces.

United Nations Offensive – September-November 1950

By 1st October 1950 the first objective of the United Nations ‘To repel the armed attack’ had been achieved. The second objective ‘To restore international peace and security in the area’ remained unfulfilled while the North Korean Army remained intact and North Korea refused the demand to surrender.

Although the United Nations had never recognised the political division of South Korea at the 38th parallel, the UN Forces nevertheless halted their advance short of the 38th parallel while the UN General Assembly considered further action (this, of course, did not apply to the South Korean Forces which crossed the parallel).

Russia said that any crossing of the 38th parallel by the United Nations meant that they would be the aggressors.

On the 4th October, the United Nations gave General Macarthur authorisation to proceed north of the parallel to destroy the North Korean Armed Forces with the proviso that under no circumstances were his forces to cross the Manchurian or Soviet borders of Korea, nor was naval or air action to be undertaken against Manchurian or Soviet territory.

While this was going on arrangements were being made for General Macarthur and President Truman to meet – the General had been in the Far East for the past 14 years during which time he had not visited the United States, and there was considerable feeling that his view of the world was very different from that held in Washington. They met at Wake Island on 15th October. Macarthur was convinced that the war was all but won, he reckoned that all resistance would be over in a few weeks; there was little chance of Chinese intervention in force – perhaps 50-60 thousand men but with no air force they would suffer great casualties. The Russians could not get any troops into North Korea before winter and Russian air support for the Chinese was just unworkable. Macarthur flew back to Japan and President Truman returned to Washington.

The next day, on 16th October, Chinese forces crossed the Yalu River into North Korea.

The plan for the offensive in North Korea was based on the United Nations supremacy at sea. The plan was to move the marines and the 10th US Army Group from Inchon by sea and land them at Wonsan from where they would drive across country to Pyongyang and Chinnampo; the South Korean Army and the 8th US Army would push up from the south towards Pyongyang.

The Navy was against the Wonsan operation; they knew the harbour was mined. There were meagre minesweeping forces available and there seemed no good reason why ground forces could not proceed north by land routes, particularly as the South Korean ground forces were proceeding north at the rate of 14 miles per day. In fact the First South Korean Division captured Wonsan on 10th October – the day when minesweeping operations began in Wonsan Harbour.

There were between 2,600 and 3,000 mines laid in the Wonsan approaches – all were of Russian manufacture. The minesweeping forces consisted of 6 minesweepers, a destroyer, an LST and a helicopter, and 3 more minesweepers joined a little later. The minesweeping operation which began on 10th October was not completed until the 25th, by which time 3 minesweepers had been sunk.

The invasion fleet which arrived off Wonsan on 19th October had to wait 5 more days before the channel could be cleared. During the wait the invasion fleet each day steamed north 12 hours and 12 hours south, an operation known to the US Marines as Operation Yo Yo.

Many efforts were made to quicken the sweeping procedures – countermining with 1,000lb bombs dropped from US Fleet carriers was not successful. Both contact and magnetic mines were used and the holdup to the invasion fleet caused RADM Smith, the landing force commander, to make a signal to Washington (CNO) which read ‘The USN has lost command of the sea in Korean waters’. A slight over definition, perhaps. In the 15 days required to clear the channel only 225 mines were destroyed. Mining was a weapon that an enemy without a navy would be bound to use, and Wonsan was a timely reminder that to neglect mine warfare, as the USN had done since the end of World War II, was to give an alert enemy a quick advantage.

22,000 marines were landed at Wonsan on the 25th – 15 days after the city had been taken by South Korean forces. On the 29th, 27,000 US troops of the 7th Division were landed at Iwon.

All in all, things progressed well – the mine clearing operations at Jhaeu and Chinnampo (in which Lieutenant Commander, now RADM, G. V. Gladstone DSC and Bar played a big part) took time but were successful. Pyongyang was captured on 21st October and by mid-November United Nations and South Korean forces were approaching the Yalu River, although resistance was stiffening and some units had outrun their logistic support.

On 24th November 1950, General Macarthur launched the 8th Army in a general offensive to end the war. It ran straight into superior forces: a Chinese Army of 26 divisions was in the line of battle and another 200,000 men were in reserve in the rear. The Chinese troops were fresh, completely organised, splendidly trained and equipped.

Although the Chinese moved quickly, luckily our strength at sea enabled evacuations to be carried out rapidly and successfully. By early January 1951, the United Nations Forces had fallen back to a line Pyongtaek-Chummunchin, but by then the Chinese were running out of steam. The UN Forces gradually pushed the Chinese and North Korean Forces back to about the 38th parallel and Seoul was recaptured. Then a pause ensued while the Chinese re-equipped for a spring offensive. (General Macarthur was replaced by General Van Fleet on 11th April.)

On Sunday 22nd April the Chinese moved; the main attack had been expected in the centre but in fact it was directed at the UN left and left centre. Two South Korean divisions collapsed which resulted in the British 29th Brigade being surrounded (well known for the stand by the 1st Battalion Gloucester Regt. and Lieutenant-Colonel J.P. Carne’s VC). The British 27th Brigade and the US 5th Cavalry then plugged the gap and the enemy was held. By the end of the month the offensive was halted and the Chinese, who had suffered tremendous casualties, withdrew out of range of US artillery which was massed at great strength. A further attack began on 16th May and again the South Koreans collapsed but the US Marines and the US 2nd Division held, and 4 days later the UN Forces went over to the offensive. Catching the Chinese off balance, they managed to push them back to the original April 1951 position, north of the 38th parallel.

On 23rd June 1951, almost a year to the day after the war had started, Mr. Malik, the Soviet representative in the United Nations Security Council stated that his government believed discussions should be started between the belligerents in Korea. On 29th June the United Nations directed General Ridgway (who had relieved General Van Fleet as Commander US 8th Army) to meet the North Korean Commander-in-Chief to discuss an armistice.

The first armistice meeting was held on 11th July at Kaesong; the meeting was organised by the Chinese and North Koreans to make it appear that they were the victors, e.g. white flags on the UN jeeps, etc. This was the first of many meetings, which continued until September 1952 when there was a complete deadlock which lasted for 199 days. There were accusations and counter accusations on both sides and it was almost impossible to make any progress. Meanwhile the war went on and there was some bitter fighting although the war on the ground was restricted to limited offensives. At sea and in the air the war continued as before.

General Eisenhower became president of the United States on 20th January 1953, and on 6th March Stalin died. Three weeks later Mr. Vyshinsky, the Russian delegate in the United Nations, announced acceptance of the United Nations armistice terms. The war was officially ended at 1000 Korean time on 27th July 1953, 37 months after it began.