By the end of 1944, most of the Japanese merchant ship fleet had been sunk, primarily by submarines and naval air forces. This merchant fleet was vital in supplying Japan with oil and other materials of war.
The Sea of Japan was the only place that the Japanese merchant ships could operate with little fear of opposition. Japan was receiving significant support from China and Korea via the Sea of Japan. Since there were only two entrances and both were guarded by extensive mine fields, it was not feasible for allied warships to enter.
The Submarine Force commander heard in 1943 that a mine detecting sonar had been developed for the mine force, but was judged not suitable for mine sweeping. At first he saw no use for that sonar in submarines. However, by mid-1944 the admiral saw the mine sonar as a possible key to enter the Sea of Japan through the guardian minefields. He importuned the authorities in Washington to make available some of those sonars to Pacific submarines. By mid-1945 sonar units were available for nine submarines all of which entered the Sea of Japan successfully and sank ships. Unfortunately, one of the submarines was sunk after torpedoing a Japanese merchant ship.
A second group of submarines was equipped with the sonar and entered the Sea of Japan in early August 1945. I had the good fortune to be the Executive Officer of TORSK (SS 423) which was in the second group and fired the last torpedoes to be fired in World War II.
A captured document made the southern entrance through the Tsushima Strait a little easier by indicating that there were 4 lines of mines and stated the distances between mines and their depth.
The mines were the moored type and were set at depths to sink surface ships and submarines. We entered the Tsushima Strait on IO August, 1945 and submerged to 150 feet at 4:20 a.m. We were, of course, a little apprehensive, but knew that the preceding group entered safely and we had good training so we were not too worried.
It took about 16Y2 hours to complete the transit. We encountered the four mine lines about as advertised. However, the range of sonar detection was not nearly as great as we experienced in practice because the extensive amount of kelp in the water caused many false contacts and tended to mask the mines. We had some scary moments, but penetrated the field without scraping any mine cables like one or more of the previous group of submarines did.
The morning after we entered and while at periscope depth we noticed a strange apparition on the horizon. None of us could figure it out until we came up higher in the water. Then we discerned seven Japanese men clinging to debris. We approached them and at first they were reluctant to come on board. We found out later that their small ship had been sunk by U.S. airplanes and they had been in the water for several days.
We succeeded in getting six of the men aboard, but the seventh tried to swim away. When he saw that his shipmates were being given good treatment, he finally allowed us to pick him up. He was so weak that our crew had to pick him up and carry him below. We were having breakfast at the time and the crew tried to give the prisoners pancakes, but the survivors were intelligent enough to mainly drink the syrup which was probably best for them in their starving condition. We put three of the prisoners in the forward compartment, three in the aft compartment and the seventh in the galley to help the cooks. The one assigned to the galley was only 16 years old and he had been the cook on his ship. He indicated that he had been on two previous ships which had been sunk. This boy became the favorite of the crew and learned a lot of English before he left the ship. More about him later.
The second morning after entering the Sea of Japan, we patrolled off an island in the southern part and sank a small merchant ship. The next day we sank another merchant ship and the fourth day August 14 we had quite a busy day.
Early that day we saw a merchant ship escorted by a single frigate. We decided to sink the frigate first with a new type of torpedo which homed in on a target’s screw noises. Our submarine was one of the first to get this new, secret Mk. 28 torpedo. We fired one torpedo which we saw hit the target’s stem and lift it up 45 degrees. We also saw a number of lifeboats pick up the survivors and luckily for them they were only a few miles from shore.
We then turned our attention to the merchant ship which was heading toward a nearby port at full speed. Before we could get in a good position to fire torpedoes at the ship, it entered port. Our captain, Commander Lewellen, said maybe we should surface and fire at it with our 5 inch gun, but fortunately decided against it when a Japanese warplane appeared headed to our area. We started to depart the area, but soon heard more ship sounds and soon saw another frigate bearing down on us. The aircraft apparently saw us and called in the frigate. The frigate apparently saw our periscope because he was headed directly toward us. We decided to fire another of the acoustic torpedoes at this frigate even though the acoustic torpedoes were designed to be fired from aft the target’s beam and our present target was heading directly toward us. We fired when the target was about 2000 yards away and went deep to evade and hoped our torpedo hit. After what seemed to be an eternity, we heard a loud explosion very close to us and then breaking up noises. If that torpedo had not hit, we would have had a very bad time. They sent another frigate out to try to locate us, but we evaded it quite easily after it had dropped a few depth charges-fortunately not close.
Since we had very little sleep for the past few days, the captain decided to go into deep water and rest for a day. The next morning we received a message that the war had ended and that there was a cease fire. We were of course happy with the news, but spirits were somewhat dampened by a following message which said that we would have to stay in the Sea of Japan until the mines had been swept from Tsushima Strait which took more than two weeks.
As you may imagine, after the hectic days before the cease fire, it was quite a change to have nothing to do. The crew started to clean the ship which had been neglected during the times at battle stations. The prisoners helped in this and because of their small size and agility cleaned places never cleaned before. Also, the prisoners had become quite acclimated to life on board. Once when an engineman had difficulty closing a valve when diving, a prisoner jumped in and helped without being asked. Another time, the boy in the galley warned a crew member about making noise when we were evading a frigate. The crew started to teach the boy English and he was a quick learner. One morning a crew member asked me to come aft to see that Tanaka, the mess cook, had learned to say .. good morning”. I went aft and said: “good morning Tanaka.” He said: “I hate marines.” Of course, the marines would be taking him when we returned to port. I made certain that they told Tanaka of the joke, because the crew really liked him. The prisoners enjoyed life on board and all gained weight and did not want to leave. When we arrived in Guam 3 or 4 weeks later they left the ship with candy and cigarettes as presents from the crew.
We returned to the Submarine Base in New London via Pearl Harbor and Panama. We did not find out until later that we had sunk the last enemy ships of the war.