The blockade of Wonsan, or the siege of Wonsan, from February 16, 1951, to July 27, 1953, during the Korean War, was the longest naval blockade in modern history, lasting 861 days. United Nations naval forces, primarily from the United States, kept the strategically important city of Wonsan from being used by the North Korean Navy.
The blockade diverted communist troops from the front line. North Korean artillery fired at the American fleet was mostly ineffective, and the city was heavily damaged by UN naval aircraft and warships.
Background
Operation Wonsan
Wonsan was a strategic point during the war, located on North Korea's southeastern coast with a large harbor, an airfield, a petroleum refinery, 75,000 people, and as many as 80,000 troops, including several artillery batteries. After the Battle of Inchon, in which General Douglas MacArthur landed on the northwestern shores of the Korean Peninsula, he ordered X Corps to make a landing at Wonsan where they would proceed west, link up with the Eighth Army and then advance towards Pyongyang, the capital of North Korea.
North Korean naval forces had been well supplied by the Soviet Union and China with all sorts of sea mines, which were used as much as possible to defend Wonsan. Soviet military advisors were also employed to create more effective mine fields. One of the first objectives of the operation was to begin plotting the locations of mines and then destroy them. That made the use of minesweepers necessary, and dozens would eventually serve in the blockade. Operation Wonsan, or the Clearance of Wonsan, began on October 10 of 1950, ten days before the landing was scheduled to take place. Rear Admiral James H. Doyle commanded Task Force 90, a fleet of dozens of American warships which were used in the clearance.
Two days later on October 12, mines sank the sweepers USS Pledge and USS Pirate, killing twelve men and wounding dozens of others, all while under accurate fire from North Korean shore batteries. The United States Navy Pacific Fleet responded by starting the production of new minesweepers in the largest shipbuilding program since World War II. Other vessels were damaged by mines and battery fire as well but the loss of the Pirate and Pledge proved to be the major engagement during the operation.
Operation Tailboard
Operation Tailboard was the codename for the United States Army landing at Wonsan, and it was found to have been unnecessary. Preparations began over 800 miles away at Inchon where on October 15, thousands of marines and soldiers, 30,184 in total, embarked transports to participate in the landing. When they arrived off Wonsan on October 20, the clearance of the mine fields was still taking place so for five days X Corps and the 1st Marine Division were forced to remain on ship to wait for a clear path to the beaches.
When it came time to land on October 25, the North Koreans had already withdrawn and the British and South Koreans were securing the area. Ultimately the landing was not needed and MacArthur was criticized for not using the X Corps in the pursuit of the retreating North Korean Army on the Inchon front. On October 19, the South Korean Army captured Pyongyang so instead of heading there the American army went north along the coast to occupy Hungnam and the Chosin Reservoir areas while the 3rd Infantry Division landed at Wonsan in November as reinforcements.
Evacuation of Wonsan
UN forces would not hold Wonsan for long: after the massive Chinese intervention in the war, Allied forces were ordered to evacuate Wonsan on December 9, 1950, taking 7,009 refugees, 3,384 military personnel, 1,146 vehicles and 10,013 tons of cargo in the process. General MacArthur's plan was to regroup in Japan before launching another offensive, while holding the Pusan Perimeter. When the North Koreans and Chinese recaptured the city, defenses were rebuilt in a more formidable way, additional sea mines were deployed and new artillery batteries were erected.
Blockade
Opening engagements
The blockade began on February 16, 1951, and would last 861 days until the signing of the armistice in July 1953. Throughout the blockade, United States Navy ships and aircraft engaged shore batteries repeatedly. Several American vessels were damaged by land based artillery fire though none were destroyed. UN Task Group 95.2 was assigned to the blockade and they first bombarded Wonsan on February 17, 1951, targeting everything used by the communists and causing heavy damage.
On February 19, the destroyer USS Ozbourn, under Commander Charles O. Akers, was fired on by shore batteries in the Wonsan area. She received two direct hits and several near misses and successfully rescued a downed pilot from USS Valley Forge with a motor boat, while he was adrift in a mine field. The boat officer of the boat received a Bronze Star for the rescue. Ozbourn eventually returned to San Diego in April 1951 for repairs and later sailed back to North Korea.
On February 24, the undefended island of Sindo-ri, in Wonsan Harbor, was captured by South Korean marines supported by two American destroyers and two frigates. Wonsan shore batteries also dueled with UN warships on March 3, but there were no recorded hits. The battleship USS New Jersey participated in her first shore bombardment mission of the war on May 20, 1951. While patrolling off Wonsan, North Korean batteries opened fire and she was struck by one shell. Slightly damaged, she sustained one man killed and two wounded, her only casualties during the war. Another shot was a near miss and passed over New Jersey from aft to port. She then responded by bombarding the enemy position until they were silenced. The type of warfare experienced at Wonsan would last throughout the war.
Operation Fireball
Operation Fireball was the code name for a bombardment of the Wonsan area from May through September. It involved the joint deployment of naval and aerial assets from the 5th Air Force which caused heavy damage to the North Koreans. On the night of May 21 and May 22, during the height of the fighting, two American LSMRs, supported by light cruisers and destroyers, fired 4,903 rockets in thirty-five minutes, further damaging the defenses of the city. UN carrier aircraft were used to fire flares while the warships focused on gunnery.
It was the first time LSMRs would be deployed in the siege of Wonsan and over time would cause heavy casualties to the North Korean garrison. Between June and September the LSMRs would discharge a total of 12,924 5-inch rockets. During the operation, the destroyer USS Brinkley Bass was slightly damaged while engaging a battery, she sustained eight casualties in the action.
Action off Rei-To
On May 24, the UN station ship at Wonsan detected several small craft southeast of Rei-To Island. In a one sided night engagement, the light cruiser USS Manchester and the destroyer USS Brinkley Bass used radar to direct their fire and broke the enemy formation. Four sampans were recovered the following day along with the bodies of eleven enemies, one other wounded North Korean was taken prisoner and the sampans were found to have been converted to minelayers, with four M-26 mines each.
USS Walke incident
USS Walke was a destroyer, under Captain Marshall Thompson, of Task Force 77 (TF-77) which was by now assigned to naval operations in the Wonsan area. On June 12, 1951, Walke was about 60 miles off the coast of North Korea, at position 38°52′N 129°25′E / 38.867°N 129.417°E, when she was struck either by a torpedo or a floating sea mine which had separated from a field. The resulting explosion severely damaged Walke's hull on her port side and 26 men were killed and 40 others wounded. Many of the casualties were blown over the side and into the water when the explosion occurred and it took a long time before all of them could be recovered. The event was the deadliest suffered by the US Navy during the Korean War.
Shortly thereafter, sailors on the nearby destroyers USS Harry E. Hubbard and USS Bradford spotted an oil slick off of Walke's starboard side so they began dropping depth charges on what they reported as being two submarines. The chase was eventually discontinued and the damage to Walke was temporarily repaired and she made for Japan. A later investigation of the incident recovered a small metal disk from the damaged ship and when analyzed it was concluded to have been part of a torpedo detonator. Walke was later repaired and returned to Korean waters the following year.
Battle of the Buzz Saw
The Battle of the Buzz Saw, as United States Navy personnel called it, was North Korea's response to the UN's attacks on Wonsan. After causing heavy damage to North Korean forces within the previous months, the situation escalated as the communists started utilizing new weapons to lift the blockade. On July 6, 1951, the United States launched another naval bombardment of the area, causing high casualties and tempting the North Koreans to retaliate with an especially heavy bombardment on July 17, 1951.
For four and a half hours the destroyers USS O'Brien, USS Blue and USS Alfred A. Cunningham engaged the batteries at Wonsan, firing 2,336 rounds of 5-inch shells. The North Koreans offered heavy resistance, and over 500 splashes were counted, but there was no serious damage to the American vessels. The next day USS Frank E. Evans engaged the batteries and received four near misses, wounding four men aboard the ship.
Operation Kickoff
Between late June through August 1951, North Korean attacks on American ships seemed to increase so the United States began concentrating on destroying enemy batteries. On June 28, the destroyer USS Henry W. Tucker received counter-battery fire while conducting a bombardment of Wonsan Harbor. She was struck by one round, causing light superficial damage and one man was injured.
A few days later on July 3, the frigate USS Everett was attacked by the batteries and took hits, killing one man and wounding seven others. The Americans responded with an attack by the Fast Carrier Task Force. In one day 247 bombing sorties were carried out against Wonsan and 600 South Korean marines raided the mainland from the island of Cho-do.
On July 6, the destroyer USS Frank E. Evans landed men on the island of Hwangto-do and then with two other destroyers, bombarded buildings and a torpedo station. USS Blue captured Kukto Island the following day and established an observation point to keep watch on North Korean positions. On July 11, in the vicinity of Yo-do island, USS Blue and Frank E. Evans were attacked, approximately fifty splashes were counted near the ships but none of them were hit. Due to the attacks, particularly the Battle of the Buzz Saw, American naval commanders decided on launching Operation Kickoff which referred to maneuvers within Wonsan Harbor, aimed at reducing the batteries.
Every day from July 17, 1951, elements of the allied fleet, assigned to bombardment groups, would sail at 5 knots (9.3 km/h) to bombard known enemy positions and continue doing so from 3:00 pm until dark. On the first day of the maneuvers, the LSMRs USS Clarion River and USS LSMR-525 received heavy, accurate fire from enemy batteries on the islands of Kalmagak, Umi-do and Ho-do Pan-do. Both of the vessels were struck by shells and damaged, but not seriously. Over 500 shells splashed in the water around USS O'Brien and she sustained at least a couple of hits. One man was injured although the damage was light. USS New Jersey and heavy cruiser USS Helena also participated in the bombardment.
On August 4, British Royal Marines installed mortars on Hwangto-do to counter the North Korean shore batteries and on August 11, USS Hopewell, using shore fire control parties, fired direct and indirect fire missions against enemy troop concentrations and transportation targets in the Wonsan area. The minesweepers USS Dextrous, USS Heron and USS Redstart came under fire by shore batteries that same day while conducting check sweep operations in the vicinity of Hodo-pando. Dextrous suffered two direct hits; killing one man, three wounded and moderate damage.