Attack on the Sui-ho Dam

The attack on the Sui-ho Dam was the collective name for a series of mass air attacks by United Nations Command air forces on thirteen hydroelectric generating facilities that took place June 23 and June 24, 1952, during the Korean War. Primarily targeting the hydroelectric complex associated with the Sui-ho Dam in North Korea, the attacks were intended to apply political pressure at the stalled truce negotiations at Panmunjeom.

The attacks totaling 1,514 sorties were conducted jointly by fighters and fighter-bombers of the United States Air Force, United States Navy, United States Marine Corps, and South African Air Force, the first time in 21 months that the separate air arms had worked together on a massive scale. It was followed seventeen days later by another series of large-scale joint attacks on the capital city of Pyongyang.

The attacks succeeded in permanently destroying 90% of the facilities struck and completely knocked out power in North Korea for two weeks, as well as reducing available power to northeast China by 23%. North Korea, however, built new facilities but did not restore its previous capacity until after the armistice in 1953. Their effect on the truce talks was also nil, as highly publicized repercussions in both the UK and the United States Congress undermined their impact.

Four attacks on a much more limited scale occurred between September 12, 1952, and June 7, 1953, causing only minor damage and little impact on the outcome of the truce talks. UN forces also exerted pressure on the North Korean infrastructure by attacking the smaller power-generating plants of the North Korean power grid during the summer of 1952 to prevent them from filling the void in power generation.

North Korea's power systems
The Sui-ho Dam (now Supung Dam or sometimes Shuifeng Dam) on the Yalu River (40.46667°N, 124.96667°W), at the time the fourth largest in the world, had been constructed in 1941 by Japan. The concrete dam was 2,800 feet (853 m) in length, 300 feet (97 m) thick at the base, 60 feet (18 m) wide at the crest, and 525 feet (160 m) in height. Its reservoir storage capacity was more than 20 billion cubic meters, and the Japanese had built six turbine generators each with a capacity of 100,000 kilowatts. The dam's generating facilities provided power for much of western North Korea and for the Port Arthur and Dairen regions of northeast China.

Three of the five other hydroelectric systems were located in proximity to each other in South Hamgyong Province north of Hungnam. Each consisted of four plants 5–10 miles (8–16 km) apart along a thirty mile (50 km) stretch of river, numbered by planners 1 through 4, with plant 1 closest to its respective reservoir. The northernmost, the Kyosen (P'ungsan) system, was on the Namdae Ch'on with its terminus at Tanch'on. The Fusen (Pujǒn) system was due north of Hungnam on the Songch'on-gang, with its four plants close together but in mountain gorges. The Choshin (Changjin) ran south and then east in the mountain canyons from the Chosin Reservoir and connected with the Songch'on-gang south of Fusen Plant No. 4.

Planning history
North Korea had six hydroelectric systems and six small thermoelectric plants at the outbreak of the war, and all were on the list of strategically important targets compiled by the Joint Chiefs of Staff (JCS). B-29 Superfortresses of the United States Air Force had begun bombing industrial targets in North Korea soon after the invasion of the South in the summer of 1950 but had not attacked any part of the power transmission grid. As early as August 23, 1950, while UN forces were still struggling to hold the Pusan Perimeter and well before the UN landing at Inchon, planners of the FEAF had asked if the hydroelectric system should be attacked, no decision had yet been made as to whether North Korea was to be occupied.

On September 21, 1950, FEAF attacked a plant of the Fusen system near Hungnam, completely destroying its transformers, and recommended that all the plants be destroyed. General Douglas MacArthur directed the attacks to proceed, but before that happened the JCS authorized MacArthur to enter North Korea and advised that targets of "long-term importance" including the hydroelectric plants should not be destroyed. A ban on bombing the Sui-ho (Sup'ung) Dam was put in place on November 6, 1950, at the direction of the U.S. State Department, to avoid providing a provocation for entry in the war by China. Even after China's massive intervention in the following month the ban was never rescinded, and it was reiterated by the UN Command when the truce talks began in July 1951.

On March 3, 1952, when the peace talks appeared to be near stalemate, U.S. Air Force General Otto P. Weyland, commanding Far East Air Forces, recommended to UN commander General Matthew Ridgway that the hydroelectric plants be attacked to "create psychological and political effects to our advantage." Ridgway rejected the plan and also informed the JCS that he was unwilling to use force except as the last resort.

On April 28, President Harry Truman announced that Ridgway was being replaced as commander in Korea by General Mark Clark, and UN negotiators at Panmunjom made a compromise proposal on the stalemated issues. The next day the JCS asked Weyland to provide target information and recommendations in the event of complete stalemate, and he repeated his recommendation to bomb the hydroelectric plants. Ridgway objected to the JCS on May 1, stating that no attack should be made except on his recommendation, to which the JCS agreed. The next day the communists totally rejected the UN proposal, and while the talks continued, the UN took the stance that their position was irrevocable.

Clark took command on May 12, the first of a series of key changes in the military command in Korea. On May 19 Vice Admiral Joseph J. Clark became commander of the Seventh Fleet, on May 30 Lt.Gen. Glenn O. Barcus took over the Fifth Air Force, and on June 4 Vice Adm. Robert P. Briscoe became commander of Naval Forces Far East. All brought a new aggressiveness to their commands and were desirous of attacking the hydroelectric plants. Briscoe made the recommendation to Clark on June 6, followed by Weyland the next day.

At Clark's direction, FEAF prepared two attack plans on the system, one of which included bombing the Sui-ho Dam while the other did not. The three systems in South Hamgyong were targeted, while two smaller systems&mdash;one near the border with the Soviet Union and the other immediately behind the battleline&mdash;were excluded. The plans, submitted to Clark on June 11, included both FEAF and Task Force 77 units, and Clark approved the lesser plan on June 17, naming Weyland as "coordinating agent". However in reviewing the plans, the JCS recommended to Truman that the Sui-ho Dam also be attacked and he approved. The JCS authorized the attack on June 19, and the alternate plan was put into effect with a tentative date of June 23 or June 24, which would allow Briscoe to use four aircraft carriers in the operation. The operations plan was finalized when Clark proposed to Weyland that naval aircraft, originally slated only for the eastern complexes, be added to the attack on Sui-ho.

UN air order of battle, June 1952
SOURCES: USAF Historical Study No. 127 and History of US Naval Operations, Korea

The following air combat units were assigned to the attacks on the North Korean hydroelectric plants:
 * Far East Air Forces - Lt. Gen. Otto P. Weyland
 * Fifth Air Force - Lt. Gen. Glenn O. Barcus
 * 4th Fighter-Interceptor Group - Col. Royal N. Baker
 * 334th FIS, 335th FIS, 336th FIS
 * 51st Fighter-Interceptor Group - Lt. Col. Albert S. Kelly
 * 16th FIS, 25th FIS, 39th FIS
 * 8th Fighter-Bomber Group - Col. Levi R. Chase
 * 35th FBS, 36th FBS, 80th FBS
 * 18th Fighter-Bomber Group - Col. Sheldon S. Brinson
 * 12th FBS, 67th FBS, 2 Sqd SAAF
 * 49th Fighter-Bomber Group - Lt. Col. Gordon F. Blood
 * 7th FBS, 8th FBS, 9th FBS
 * 136th Fighter-Bomber Group -Lt. Col. Donald F. Sharp
 * 111th FBS, 154th FBS, 182nd FBS
 * 1st Marine Aircraft Wing - Maj. Gen. Clayton C. Jerome
 * Marine Aircraft Group 12
 * VMA-121, VMA-212, VMA-323
 * Marine Aircraft Group 33
 * VMF-115, VMF-311
 * Naval Forces Far East - Vice Adm. Robert P. Briscoe
 * Seventh Fleet - Vice Adm. Joseph J. Clark
 * Task Force 77 - Rear Adm. Apollo Soucek
 * Carrier Division One - Rear Adm. Herbert E. Regan
 * Carrier Air Group Seven, embarked on USS Bon Homme Richard (CV-31) - Cmdr. G. B. Brown
 * VF-71, VF-72, VF-74, VA-75
 * Carrier Air Group Eleven, embarked on USS Philippine Sea (CV-47) - Cmdr. J.W. Onstott
 * VF-112, VF-113, VF-114, VA-115
 * Carrier Division Three - Rear Adm. Soucek
 * Carrier Air Group Two, embarked on USS Boxer (CV-21) - Cmdr. A.L. Downing
 * VF-24, VF-63, VF-64, VA-65
 * Carrier Air Group Nineteen, embarked on USS Princeton (CV-37) - Cmdr. William Denton, Jr.
 * VF-191, VF-192, VF-193, VA-195

Soviet air order of battle, June 1952
The Soviet Air Forces (VVS) order of battle on June 23, 1952, was two fighter aviation divisions (USAF wing-equivalent), totalling five regiments or from 150 MiG 15s. Per the second source, the Soviet fighter aviation regiment was the equivalent of an over-sized USAF squadron or an under-sized USAF group (24-36 aircraft).
 * 97th IAD (Fighter Aviation Division) PVO 
 * 16th IAP (Fighter Aviation Regiment)
 * 148th GIAP (Guards Fighter Aviation Regiment)
 * 190th IAD (Fighter Aviation Division) PVO
 * 256th IAP (Fighter Aviation Regiment)
 * 494th IAP (Fighter Aviation Regiment)
 * 821st IAP (Fighter Aviation Regiment)
 * 351st IAP (Independent Fighter Aviation Regiment) VVS

Another fighter division was based in rear areas at Mukden and Anshan, with four additional regiments and approximately 90 MiG-15s. These units were primarily in training and were not operational until July 12. The 37-mm guns of the PVO 87th ZAD (Antiaircraft Artillery Division) were responsible to provide local anti-aircraft artillery defense to Sui-ho, Choshin, Fusen and Kyosen.

Target assignments
SOURCE: The United States Air Force in Korea, p. 487

SOURCE: Carrier and Air Group Action Reports

First day missions
Task Force 77 had four aircraft carriers available for the attacks. USS Philippine Sea (CV-47) was already on the line during the planning process, joined by USS Princeton (CV-37) on June 2 and USS Boxer (CV-21) on June 9. Rear Adm. Apollo Soucek was aboard Boxer and took operational command of Task Force 77. When Weyland approved Navy participation in the Sui-ho strike, USS Bon Homme Richard (CV-31) sailed from Yokosuka, Japan, on June 21 to provide the added force needed, arriving early on June 23.

The mission was to be launched at 08:00 June 23 (all times local time zone), with strikes beginning at 09:30 at all targets. However weather reconnaissance aircraft reported unbroken clouds over the Yalu River, and Weyland postponed the attack at 07:40. As the morning passed, however, the weather system moved south, and Weyland immediately reversed himself and at 13:00 ordered the attacks to proceed, using the heavy clouds as concealment for the attackers en route to their targets, with a new attack time of 16:00.

Aircraft from all four U.N. services were a mixture of propeller-driven and jet aircraft, and in general the propeller aircraft launched up to an hour earlier than the jets to coordinate their arrival over the target together. The carriers launched their propeller aircraft at 14:00 and their jets at 15:00. Air Force fighter-bombers, having the longest distance to fly, took off at 14:30. Because the Sui-ho Dam was located less than forty miles (65 km) from the MiG 15 fighter base complex at Antung/Tai Ton Chao/Phen Chen in China, where 150 MiGs had been counted by the weather reconnaissance, a coordinated simultaneous arrival over the targets was crucial to limiting the effectiveness of any defensive reaction.

The carrier aircraft of TF77 crossed the Korean coast at Mayang-do northeast of Hungnam and flew low over the mountains at 5,000 feet (1,500 m) to mask their radar signature. The propeller and jet divisions rendezvoused approximately 50 miles (80 km) east of Suiho shortly before 16:00 and climbed to the attack altitude of 10,000 feet (3,000 m) for a high-speed run-in.

Eighty-four F-86 Sabres of the 4th and 51st Fighter-Interceptor Groups were the first to arrive in the Sui-ho target area, to provide cover against MiG attack and, according to one participant, with part of the force ordered to keep MiGs from taking off by flying low over their bases, even though officially UN aircraft were not allowed to cross the Yalu except in hot pursuit. According to US sources, 160 MiGs that took off before the arrival of the covering force flew deeper into China, possibly fearing the airfields were the targets, and none attempted to intercept the strike force.

Incursions into Manchuria by pilots of the 51st FIG to surprise MiGs over their own airfields had resulted in heavy losses for the 64th IAK during the previous months, with at least half of the MiGs destroyed in April and May 1952 shot down during take-offs or landings. The Soviets developed a counter-tactic to cover takeoffs from Antung with combat air patrols launched from Mukden and Anshan, but on June 23, despite good weather over Antung, inclement conditions prevented covering MiGs from taking off. In turn, this prevented Soviet fighters based at Antung from countering the strike to avoid pointless losses during takeoffs.

At 16:00, 35 Navy F9F Panthers began runs to suppress the anti-aircraft fire from 44 heavy caliber gun and 37 automatic weapons emplacements reported around the dam. Twelve AD Skyraiders of VA-65 off Boxer then began their dive-bombing runs on the Sui-ho generating stations, followed by 23 Skyraiders off Princeton and Philippine Sea, releasing 81 tons of bombs in little more than two minutes.

Between 16:10 and 17:00, U.S. Air Force jets added 145 tons of bombs on the Sui-ho generating plant with 79 sorties by F-84 Thunderjets of the 49th and 136 Fighter-Bomber Groups and 45 by F-80 Shooting Stars of the 8th Fighter-Bomber Group (8th Fighter-Bomber Wing).

At almost the same time, 52 F-51 Mustangs of the 18th Fighter-Bomber Group and the South African 2 Squadron struck Fusen plants 3 and 4, west of Hungnam, while 40 Marine Skyraiders and F4U Corsairs of MAG-12 bombed Choshin No. 4, and 38 Panthers of MAG-33 hit Choshin No. 3. The lower Fusen plants and the Kyosen complex were bombed by 102 Corsairs, 18 Skyraiders, and 18 Panthers off the carriers. In all on June 23, Task Force 77 flew 208 strike sorties and FEAF 202. At 19:00, two RF-80 photo-recon aircraft of the 67th Reconnaissance Group, escorted by six flights of F-86s, returned to Sui-ho, while Marine F2H-2P Banshee photo-recon planes of VMJ-1 and Navy F9F-2P Panthers of VC-61 overflew the eastern systems to assess damage.

Two F-80s of the 8th FBW were battle-damaged by flak over Sui-ho, and written off after crash landings in Taegu. An F4U flown by the squadron commander of VF-63 (from Boxer) was heavily damaged over Kyosen No. 4 and made a water-landing in which the pilot was rescued, the only naval plane lost. A VA-115 Skyraider (from Philippine Sea) had its hydraulic system damaged by flak over Sui-ho and diverted to K-14 airfield at Kimpo, South Korea, for a wheels-up landing, and another from VA-75 was severely damaged when it was struck by debris from a bomb explosion but recovered aboard Bon Homme Richard. The only other battle damage reported by the attacking units was by Carrier Air Group 11 off Philippine Sea: a Corsair hit in an accessory compartment over Kyosen No. 3, and a Skyraider at Sui-ho struck by small arms fire.

Second day missions and damage results
Although interpretation of reconnaissance photos and assessments by returning pilots indicated heavy damage to the Sui-ho, Choshin, Fusen, and Kyosen No. 1 and 2 plants, most of the targets were re-struck the next day, June 24, in both morning and afternoon missions.

In the morning missions, Air Force F-84s and Navy Skyraiders attacked Sui-ho, judging it totally destroyed, with one Skyraider suffering minor damage. Princeton aircraft bombed Fusen, Mustangs of the 18th FBG hit the unscathed Choshin plants 1 and 2, and planes off Boxer and Philippine Sea struck the remainder of the Kyosen plants.

In the afternoon Princeton completed the destruction of Kyosen No. 3, but incurred the loss of a Corsair of VF-192 in the process, although the pilot was rescued at sea. Soviet records claimed that the loss of an F-86E of the 335th FIS, written off after its return to Kimpo, was the result of a MiG attack by a Soviet pilot. Aircraft from the other three carriers struck transformer stations along the power grid at Chungdae-ri, Naemǒkpang, and Man'gyo-ri, in the vicinity of Kojǒ (Kangwon Province), and at Yuchǒn, Haeju, Chaeryong, Kaishu, and Chang-yôn in North Hwanghae Province.

Choshin and Fusen were re-attacked by smaller numbers of Air Force fighters on June 25–27 to complete the attacks. Total bombing sorties were 730 by land-based fighter-bombers and 546 by carrier aircraft. F-86 Sabres flew an additional 238 counter-air sorties to protect the force from MiGs.

Approximately 90% of North Korea's power-production capacity was destroyed in the attacks, with 11 of the 13 generating plants put totally out of operation and the remaining two doubtful of operating. China suffered an estimated loss of 23% of its electric requirements for northeast China, and other intelligence estimates stated that industrial output in 60% of its key industries in the Dairen region failed to meet production quotas. For two weeks North Korea endured a total power blackout.

Both China and the Soviet Union immediately sent technicians into North Korea to repair or re-build loss generators. For much of the summer of 1952 only approximately 10% of former energy production was restored, primarily by its thermoelectric plants.

Political effects of June attacks
What effect if any the attacks had on the communist hierarchy and its representatives at the truce talks was immediately negated by reaction of the left wing in London. In the Parliament of the United Kingdom, Labour Party leaders Clement Attlee and Aneurin Bevan criticized the operation as risking World War III, even though there were no allegations of territorial violations or objections that the plants were non-military targets.

The Labour Party saw an opportunity to cripple the ruling Conservatives and immediately called for a vote in the House of Commons to censure the Churchill government, but based on the British government's "failure to secure effective consultation" from the U.S. beforehand (The Minister of Defence, Lord Harold Alexander, had been in Korea when Clark first approved the FEAF plan but had left Korea before the JCS input). The government barely survived the vote after U.S. Secretary of State Dean Acheson publicly took the blame, stating the U.S. was at fault for not consulting the British "as a courtesy", although the price for this stance was undercutting Clark and the Panmunjom negotiators. Naval historian James Field commented that cooperation between the services was much smoother than between the allies.

While conferring with Alexander, Clark had already agreed in principle to British requests for a representative of the UN staff, and Churchill's designee was appointed as a deputy chief of staff on July 31, 1952.

The other factor crippling the political effect of the strikes occurred in the United States and was just the opposite of that in Britain. Critics of the Truman administration in Congress quickly seized on the military success of the strikes to question why the attacks had taken almost two years to be approved. General Clark, who agreed, so advised the JCS. Secretary of Defense Robert A. Lovett, to whom the inquiries were made, cited seven factors, but some were long obsolete by the time of the attacks and others clearly badly estimated.

Despite the lack of political effect on the truce talks, and the widely publicized negative reactions on both sides, the campaign against the hydroelectric system became an acceptable tactic of UN forces.

Summer 1952 power grid campaign
Within ten days of the strikes, UN air forces renewed attacks to keep the power grid out of service, although the Sui-ho Dam and its environs were not among the targets.

Task Force 77 renewed its attacks on July 3 by attacks of Navy aircraft from the carriers Philippine Sea, Bon Homme Richard, and Boxer. Both Kyosen power plants were targeted, as were three power plants at Puryŏng-ŭp (Funei). The latter, previously unstruck, had been scheduled to be bombed on June 29 but the mission had been cancelled by fog in the target area. Bon Homme Richard's Air Group Seven further damaged Kyosen No.1, but smoke obscured Kyosen No.2, and it was restruck on July 8, destroying its powerhouse and penstocks (piping that delivers water to the turbines). USAF F-84s of the 49th FBW attacked the Choshin plants on July 8, striking the generators, transformer yards, and penstocks in 41 sorties.

On July 19, Air Group Seven's aircraft bombed Choshin No. 3, scoring five hits on its transformer yard, while Air Group Nineteen aboard Princeton bombed Choshin No. 1, and again on July 20, noting a significant increase in AAA defenses. On July 23, the thermo-electric plant at Wonsan was attacked for the first time, by aircraft from Bon Homme Richard, which reported it completely destroyed. On the nights of July 19–20, and July 21–22, 44 B-29 sorties were flown against Choshin No. 2.

Air Group Seven attacked Puryŏng-ŭp No. 3 on July 26, the Kojǒ No. 3 transformer yard on July 31, Choshin No. 1 on August 1, Kyosen No. 2 on August 3, and Kyosen No. 1 on September 21. A newly activated air group, Air Task Group Two (ATG-2), aboard USS Essex, also attacked Kyosen No. 2 on August 3, then struck Choshin No. 1 and Kyosen No. 1 on August 5. In the fifteen attacks by the Navy, no carrier aircraft were lost. Further B-29 sorties were directed against Choshin No.1, sixteen on the night of August 29, and fifty on the night of September 1.

September 12, 1952
The United Nations renewed its attacks on the Sui-ho hydroelectric complex with a night attack on September 12, 1952, organized into three forces: a flak/searchlight suppression force of B-26 Invaders and naval aircraft of USS Princeton, an electronic counter-measures force of four specially modified B-29 Superfortresses to jam Soviet AAA radars and communications, and a bombing force of 25 B-29s of the 19th and 307th Bomb Groups using SHORAN navigation aids to locate the target.

After the take off at 19:00 hrs, the bomber force suffered its first setback when an unexpected cold front caused icing in the upper surfaces of wings and fuselage of some B-29s. One of the bombers stalled and crashed 19 miles (30 kilometers) north of Kangnung, killing all but one of its crew. The flak suppression forces were able to locate and attack only eight searchlights, and flak shot down an F4U of VF-193.

The B-29 force arrived at Sui-ho at 23:55 hrs, but in spite of the jamming by the ECM aircraft encountered a dense flak barrage. A B-29 of the 307th BG was shot down by a MiG-15, with only one crew member surviving as a POW, and another of the 19th BG was damaged. Two others were hit by flak, making emergency landings at Taegu AB, South Korea. The intensity of AAA fire and MiG attacks dispersed the bomber formation with a consequential loss of accuracy. The Soviet after-action report stated:

''Up to 500 bombs weighting 250/450/1000 kgs were dropped on the target. Three bombs hit the upper part of the dam, one hit the part of the turbine room which had been already destroyed, and up to 50 hit the previously destroyed transformer facility. The remaining bombs missed the target by 1-2 km to the southeast. In addition to high-explosive bombs, the enemy used incendiary and napalm bombs. The dam, the working turbines, the generators and the transformers were not damaged. The shock waves destroyed a high-voltage overhead cable and six peasant huts. The warehouse storing the POW’s food burned down. One local man was killed and two were wounded.''

Despite initial USAF estimates claiming five hits on the main powerhouse and three on the transformer yards, photo reconnaissance on October 12 reported that the complex was still in limited operation, indicated by the flow of tailrace water from two turbines.

February 15, 1953
Reconnaissance photographs of tailrace activity continued to indicate that two generators of the Sui-ho hydroelectric complex remained in operation. A low-level attack by 24 F-84s of the 49th FBG on February 15, 1953,  carrying two 1000-pound bombs each and escorted by 82 F-86s, struck the complex without loss. However, the escorts were attacked by 30 MiG-15s, and in the ensuing combat the Soviet 913th IAP claimed two F-86s shot down, and admitted the loss of one MiG. Escorting F-86s, however, claimed four MiGs shot down and reported no losses.

May 10, 1953
Eight F-84s of the 474th FBG attacked Sui-ho again on May 10 without loss, placing three delayed-action bombs in the power house. In air combat among the escorts and interceptors, the Chinese People's Liberation Army Air Force claimed an F-86 shot down, with its own MiG-15 pilot subsequently shot down killed. However, 4th FIW pilots claimed two MiGs shot down with no losses that date.

June 7, 1953
The final attack of the Korean War on the Sui-ho hydroelectric complex was made on June 7, 1953. A force of eight F-86F fighter-bombers from the 8th FBG, in "integral flight formation" with twelve of the 51st FIG to disguise its mission, flew as part of the Yalu River patrol by 66 other F-86s. The fighter-bomber formation reached the Sui-ho Reservoir, a common F-86 checkpoint, then rolled into its bomb run, surprising the defenders. Although several hits were reported, tailrace activity observed several days later indicated two generators were probably operating, and further attacks were discontinued for lack of intelligence of their location within the vast powerhouse.

A private source alleges that in connection with this mission, F-86s of the 4th FIG entered deep into Manchuria to ambush the Soviet MiGs while they were taking off, shooting down two MiGs of the 535th IAP, and that part of the 535th IAP evaded the blockading Sabres to engage the escort, damaging an F-86E of the 51st FIG beyond economic repair. The 781st IAP TOF claimed an F-86F of the 67th FBS as destroyed when it was written off after return to base. USAF records, however, claim that the aircraft was a total loss after a tire failed during landing, and that its fighters shot down five MiGs.

The purpose of the strikes was to remind the communists that the UN intended to make continuation of the war as expensive as possible for them. Sui-ho's No. 6 and 7 generators, and that of Choshin No. 1, were back in operation at the time of the armistice.