The idea of obtaining a certain hit by torpedoes fired from a submarine but driven by a volunteer took shape at the time of the first Japanese attack on Pearl Harbor, when five midget submarines were employed. Several tiny submarines were built for trials carried out on an island known under the code name of “Base P,” near Kure Naval Base.
By January, 1943, the “human torpedo” project had reached the stage when designs could be put forward. The first of these involved certain death for the operator, a fact which the Japanese naval authorities were not prepared to accept. A device was therefore added which, on pressing a button some hundred and fifty feet before reaching the target, threw the operator into the sea. The prototype put up to the Naval Staff in about February, 1944, was accepted. These suicide weapons offered the hope of compensating in part for the heavy reversals being sustained at that time: Saipan Island had already fallen to the enemy and many heavy losses had been suffered. Although there were considerable doubts as to the success or failure of this new weapon, it was named “Kaiten,” which means “the turn toward heaven,” and in this mood of anxious hope, construction began at the Kure dockyard torpedo experimental depot.
While this was going on a trials base was established in Tokuyama Bay with a rear admiral to command a unit embracing all small-type submarine training.
Alas! on the first day’s trials, one of the principal advocates of this type of craft who had volunteered for the job went to his death in Tokuyama Bay, together with his co-operator: the nose of the boat stuck in the mud and it could not be surfaced. This boded ill for the future of the new weapon.
Nevertheless, frenzied training was carried out for two months, and on November 8, 1944, the Kikumizu unit was formed and left for operations. The human torpedoes were split up between three parent submarines, I-36, 47, and 37, the first two proceeding to Ulithi and I-37 to the Kossol Passage near Palau Island.
I-36 and I-47 made the approach to Ulithi according to plan on November 19. Reconnaissance confirmed that a large U.S. force of over a hundred vessels, including aircraft carriers, battleships, and other craft were at anchor. The human torpedoes were launched at 4:30 A.M. on the 20th, one from I-36 and four from I-47. The senior officer of the unit, whose torpedo was launched from I-47, was one of the strongest advocates of the use of this weapon, and before his departure he left behind him the following message:
“Daylight observation disclosed over a hundred ships at anchor in Ulithi. Though this provides a golden opportunity for the use of our human torpedoes, there are but two submarines and eight human torpedoes—a very regrettable matter.”
At the time of launching he carried in his pocket a photograph of his fellow officer, killed during the trials, and on this, his first operation, showed great firmness of purpose. Before embarking he expressed his gratitude to the captain of I-47 for having confirmed the enemy strength and brought the boat to the most favorable position for launching. He wished I-47 a long life and with a firm handshake he embarked in his torpedo, saying, “Thank you for all your help. Give my regards to the boats that follow me.” Alas! Nothing was ever heard of the results he achieved, nor was his fate known.
I-36 and 47 returned safely to Kure on December 1, but I-37, which had proceeded to Palau, failed to return.
Although the results achieved by the Kikumizu unit had not been ascertained, much was expected of the Kaiten, and a further unit, the Kongo unit, was formed with the six remaining large submarines of the latest type.
The instructions issued for this unit called for I-36 to proceed to Ulithi, I-47 to Hollandia, I-56 to Admiralty Island, I-53 to Palau, and I-58, the boat I commanded, to Guam Island; all were to attack on January 11, 1945. I-48 was to attack Ulithi later on January 20.
Fifteen of us had graduated in the submarine course at the naval college, but by this time most of my class had been killed in action and there were only five of us left. Oddly enough, of the six submarines in the Kongo unit, five were commanded by the remaining five members of my class.
The Kaitens had been built in conditions of great secrecy, but we knew they had already been used in the first attack on Ulithi. An officer operating one of them wrote:
“The future use of human torpedoes will be fraught with difficulty. The more we use our opportunities for attack the more must we pay careful attention to the method of employment of this craft.”
In other words, it had to be assumed that the Americans were aware of this form of attack, so we could expect that, after the second attack, our adversary would be well on his guard. Thus both the approach of the submarine to the launching position and the actual penetration of the Kaiten to its target became a much more hazardous affair. And so, in fact, it proved.
My own submarine, I-58, having completed preparations at Sasebo, proceeded to Kure to take in fuel, provisions, and torpedoes. On December 29 she sailed for the human torpedo base where all ranks were addressed by the Admiral Commanding Submarines. We took a photograph to commemorate the occasion, and after a grand send-off I-58 left harbor in company with I-36 and 53, accompanied also by a host of crowded motor boats whose occupants were chanting in unison the names of the personnel of the departing unit. The human torpedo pilots were sitting in their respective craft, wearing white towels round their heads and brandishing their swords.
On board the submarine, the mark I-58 had been erased and replaced by the Kongo unit badge. At the masthead, beside the ensign we flew a flag bearing the inscription, “The unpredictable Kaiten.”
We passed through the Bungo Channel and turned south, proceeding on the surface. Through the evening haze we took a dramatic farewell look at the homeland; then even the outlying islands disappeared far beyond the horizon.
Enemy submarines were at large in the area, so a strict lookout was necessary. We commenced zigzagging and proceeded through the night at increased speed. We were using for the first time an antiaircraft radar set, but although it had been adjusted while in sight of land, we found it wasn’t working very well. A man had to be sent on deck to make some repairs as we were particularly anxious not to be spotted. The night passed, and it was the first of January, 1945. The boat was getting some help from the northwest trade winds. The sunrise that morning at sea was indeed a magnificent sight. Alcoholic drinks were normally forbidden at sea, but this was a special occasion, so permission was given to serve enough sake to drink toasts. After the boat had dived, cheers for the Emperor could be given and toasts drunk without any qualms.
During the voyage to the target the two Kaiten officer pilots were always together for meals, but the warrant officers messed with the crew and we didn’t normally see them. Today, however, they were summoned to the wardroom and we all fed together.
From January 2 we were in range of enemy patrols from Saipan and Guam and we submerged at times when enemy aircraft were expected. This same day, while using the radar set, an enemy aircraft was sighted through binoculars. It was clear that the radar set was still unreliable! The lookouts were accordingly warned to keep a very strict watch for aircraft.
Since its recapture by the Americans, it seemed that Guam had assumed great importance as a Central Pacific base. Even though our present operation wasn’t known, we could expect very careful precautions to be taken by the enemy in view of the earlier attack on Ulithi. The best plan, therefore, was to make a detour and approach from a quarter where the defenses could be expected to be light. This involved proceeding further to the south and approaching on a line joining Ulithi and Guam, in other words to make the approach from the enemy quarter. As we were nearing an enemy base, submerged periods grew longer and those on the surface shorter. On January 7 we passed the enemy line of communications between Guam and Ulithi, and we remained a long time submerged, keeping a very strict lookout. There was no question of any submarines in the unit attacking the enemy before launching her human torpedoes; her sole object was to remain hidden.
During long periods submerged there was little to do on board. The two Kaiten pilots had no duties beyond preparing their torpedoes and periscope drill, and they took to playing chess. One of them had been present on the occasion of the Ulithi attack but was unable to take an active part because of a defect in his torpedo. He was a very good chess player. The other was a term mate of our gunnery officer and was fat and composed, sitting astride his torpedo and brandishing his sword.
When he was at the naval college, I can well remember him coming to my submarine (I-58) for training. That was in 1943, so barely two years had passed. The same pupil had now become a sub-lieutenant and yet he couldn’t be more than twenty-one or twenty-two. It was very sad to think he was billed for certain death in this attempt to turn the tide of war. Painful though it was to think of sending out these men on such expeditions, the times were such that the number of those who did not return were growing apace in fields quite outside special units, and both old and young alike were departing from this world. In such a situation, sooner or later, their fate was inevitable.
On the 6th we arrived on the line of communications between Guam and Leyte. At 2 A.M. an aircraft showed up on the radar and we dived and proceeded submerged. Up to now we had managed to dodge enemy aircraft, but now we were near our objective and on the main traffic route, and we might well have met with aircraft unexpectedly. We should have been able to depend on our radar, but it was too unreliable to give due warning. Thus we had to proceed submerged and only surfaced at 2 P.M., which was the time we could expect a gap in the attentions of enemy patrol aircraft.
The weather was fine and calm, with a gentle breeze, and morale was high. Although it was January we were wearing tropical clothing. In the sea we noticed many boxes and empty drums bobbing about. We went cautiously on the surface, alert, expecting to be sighted. Surprisingly we were able to proceed on the surface for an hour and a half during that afternoon, and we charged our batteries and changed the air in the boat before diving at 3:30 P.M. This made up for our having to dive by night. We had decided to surface each day at five o’clock in the afternoon on the supposition that the enemy patrol aircraft reached their farthest position and turned back at about noon. There must have been some truth in this, as we never met with an enemy aircraft then. There is usually an unexpected loophole like this, but it would have been unwise to follow the same procedure all the time on approaching our objective.
That night, January 6, we surfaced at 10 P.M., the time when we reckoned that the enemy night patrol would have returned to base. About 10:30 P.M. several patterns appeared on the radar screen, and the lookout reported a dark object, probably a ship, in the direction of a squall at a range of about one hundred and fifty yards. We dived hastily without stopping to investigate. Nothing was heard on the hydrophones, but we continued submerged. From the next day, the 7th, we surfaced earlier in the day and only once during the night between 9 P.M. and 4 A.M. At last the day of the operation was almost due: it was January 9. Afterward we learned this was the day the enemy began their landing in Lingayen Gulf in Luzon, the main island of the Philippines.
We had been given an air reconnaissance report on Guam, but there was nothing in it about the ships at anchor there, and we were somewhat apprehensive. However, an earlier report had given the ships at anchor as one aircraft carrier and sixty to seventy other vessels, so we had reason to hope that there would be one or two big ones still there. On the 10th we received confirmatory orders from the C.-in-C. to carry out the attack as planned, and I passed on this news to the Kaiten pilots. At about 2 A.M. on the 11th we sighted the exhaust trail of an aircraft passing at short range and we dived. Normally we could estimate the times of arrival and departure of enemy patrol aircraft by listening in on their radio communications wave, and there shouldn’t have been one about at this hour. Possibly this one was the Ulithi area communications aircraft. At any rate we had estimated that there shouldn’t have been a patrol aircraft on this course. Since the 6th we had sighted many ships and aircraft, but believed that we ourselves had passed unseen. If the enemy had seriously carried out a sweep, we could have offered no resistance. But once again we couldn’t place much reliance on our air radar.
At about 9 A.M. on the 11th we heard the sound of the reciprocating engines of what seemed like a merchant ship proceeding unescorted. That was proof that the enemy didn’t know about us, and two hours later we reached a position from which Guam should have been just in sight. The periscope was raised cautiously. At first I thought the blur was only a cloud, but closer inspection revealed without doubt that it was Guam. The navigator had done his work splendidly—it was Guam, and we were still twenty-six miles off.
I pointed out the distant target to the Kaiten pilots, and then we dived and made straight for the launching position. From time to time we heard the sound of propellers of probable merchant ships, but all were unescorted. The enemy was quite unsuspecting. At dusk we raised the periscope once more, but could see nothing owing to a squall. At 9 P.M. we sighted a large merchant ship passing close, but we were forbidden to take any action. We were not zigzagging. At supper that night we drank the healths of the Kaiten pilots and toasted to their success.
At 9:43 P.M. we surfaced at an estimated distance of eleven miles to the west of Apra harbor on the island of Guam and made for the launching point at seven knots. A final inspection of the torpedoes was made. Thirteen minutes after surfacing, our W/T officer reported that he had intercepted an enemy message from Guam W/T station, reporting the sighting of a suspicious vessel. Could this mean I-58? We had still two hours to run so there was nothing to do but to press on.
Our air reconnaissance report of the 9th showed that there were present at Guam twenty large and forty small transports and four floating docks: not much in the way of big prizes. One felt sorry for the human torpedo pilots, but I told them to search for the largest transport, which was heavily loaded, and also explained that the floating dock somewhere in the corner was not without its merits as a target. I also consoled them by saying that an aircraft carrier might have come in since the report was made on the 9th.
One of the officers left behind a statement which I remembered for a long time:
“I wanted all the details of the photographic reconnaissance. Was it not irresponsible to send us into the attack without giving us some idea of the enemy’s defenses or the conditions inside the harbor?”
Anyway it seemed that the enemy had really sighted us at last. The pilots of Numbers 2 and 3 torpedoes could only embark from the upper deck and I gave the order for them to get into their craft at once for fear of the enemy catching us in the act. It was cloudy but the stars were bright. In the darkness their faces were invisible when the two pilots, wearing shorts, came on the bridge to report. For a while they stood there in silence. Then one said, “Captain, which is the Southern Cross?” His question took me by surprise. I searched the sky but couldn’t find the constellation. I asked the navigator, who was familiar with such things by virtue of taking daily observations, but he said the cross wasn’t showing yet, though it would appear shortly to the southeast. The pilots, saying simply, “We embark,” shook hands in resolute manner and went down from the bridge.
By now Guam Island was a pitch-black mass lying straight across our path. After a little while a puff of white smoke rose up, apparently from the island. At 11 P.M. we increased to twelve knots—there was still an hour to go for the launching position. At midnight, strong impulses appeared on our radar screen, seeming to come from two different places. Was it an enemy ship or had they sighted us from shore? Anyway it looked as if their radar had picked us up. We didn’t know our position accurately and it would have been fatal had we been too far off. For better or for worse I proceeded in the direction of the enemy, using my radar to check our distance from the shore. It turned out to be just seventeen miles, as planned. I prepared to dive forthwith, hoping to effect the launching before the enemy could get in an attack, but a report came from the engine room saying that water was coming in through the exhaust and that we couldn’t remain submerged. There was nothing to do—we surfaced. We could still hear the enemy radar and our position was distinctly uncomfortable. In ten minutes repairs were effected and we were able to dive. While all this was going on, we were getting telephone messages from the Numbers 2 and 3 pilots who had already boarded their craft. At 2 A.M. I showed the two pilots of torpedoes Numbers 1 and 4 the lights of Guam through the periscope and, wishing them luck, gave them orders to board also. Even now the composure of the two young men remains fixed in my mind. The man whose duty it was to close the bottom flap of the torpedo finished his job and raised his hand to signal all set. At 2:30 A.M. the order was given, “Stand by to launch.” Each torpedo aligned its rudder with the submarine. Until the moment of launching communication was by telephone so arranged that the connection could be ripped off when the torpedo left the parent ship.
Ten minutes later, all were ready to launch and we prepared to release the torpedoes in order. The actual time planned for launching was 3 A.M. By 4:30 A.M. it would begin to get light and by the time the torpedoes were due at their objective it would be full daylight.
Torpedo 1 reported, “All well.” The last clamp was let go, her engine started, and the weapon was launched. The pilot proceeded on his way, his last contact with us, the telephone, finally severed. There she went in full cry for the enemy ships in the harbor at Guam. At the very last moment the officer pilot shouted, “Three cheers for the Emperor.” Number 2 Kaiten was then launched in like manner. Despite his youth the pilot was composed to the last and went on his way without uttering a single word. Torpedo 3 was delayed till last, for too much water got into the engine, so 4 was launched third, amid more shouts of, “Three cheers for the Emperor.” Finally Number 3 went off. Owing to a defect in the telephone it was impossible to have a final word with her pilot.
At that moment a loud explosion was heard which might have come from Number 3. We surfaced but all was well and we made for the open sea to escape. At 4:30 A.M. torpedo 1 was due at her target. We tried to see what was happening at Apra harbor but just at that moment an aircraft appeared and we had to dive and make off. We were not, however, attacked.
We tried to listen on the hydrophones for the sound of the torpedoes hitting their mark. After dawn we came to periscope depth and made a search to the east but it revealed only something resembling a dark cloud or smoke; nothing that could be confirmed. We remained submerged till 11 P.M. that night. At supper we prayed for the souls of the four warriors and afterward put their effects in order.
One of them, Lieutenant Ishikawa, had written the following, just before his torpedo was launched:
“The day of decisive action together with three other men on board has arrived. We are all well and in good spirits. Apra is going to be amazed. The moon is pale and the stars sparse and distant. In early January, O Miya Island (Guam), appearing to be silent in sleep, floats before me. Who knows the confusion there will be in a few hours’ time? For the sake of our great country we have come to the place appointed.”
“Only twenty-two years of life and it is now just like a dream. The meaning of life will be shown today. As the point of the decisive fight between Japan and America, just to check in one blow our decline and thus to protect for ever the illustrious three-thousand-year-old history of Great Japan.”
“Great Japan is the land of the Gods. The land of the Gods is eternal and cannot be destroyed. Hereafter no matter, there will be thousands and tens of thousands of boys and we now offer our lives as a sacrifice for our country. Let us get away from the petty affairs of this earthly and mundane life to the land where righteousness reigns supreme and eternal.”
One of the other pilots wrote:
“Although there is always Divine Grace over our Imperial country, nevertheless without effort there is no sincerity, without righteousness and honesty there will be nothing of value. Thereafter, even if we vainly rely on the Divine Grace it will still be dangerous.”
“Great Japan is determined to win. The decisive battle has sprung on to the enemy’s territory. May the spirits of the departed in Heaven witness our fight to the bitter end.”
With a feeling of anti-climax we set off on our long trip home, steering north in the direction of the Bungo Channel. It would have been in order to attack the enemy on the return journey but having stirred up the mud, I did not think there would be a chance of anything without waiting about for it. We went straightaway northward to have a look, but our routes were for the most part definitely laid down so as not to risk confusion with other submarines and it was not for me to go round searching for targets to suit my own book.
On the 14th we received the results of a photographic reconnaissance made on the 9th. There was then still one aircraft carrier at anchor and the thought that she would have left before the human torpedo threat filled me with regret. Until the 15th we only surfaced by night but had no encounters with the enemy. Orders to return were received by those submarines who had been unable to make their attack by the 14th.
On the 16th I reported by signal, “Attack carried out according to schedule on 12th. All torpedoes launched. Results of attacks not confirmed.” It was the first transmission since leaving harbor. That evening after proceeding submerged for about four hours, we heard the sound of turbines on the hydrophones. The tubes were brought to the ready. It was a pitch-dark night and there would have been nothing for it but a blind shot. At this point the sound vanished. Then we heard something different, a diesel, but this also disappeared. By January 19 we were fairly far north and it was getting cold. Just after noon we sighted a large aircraft and dived to safeguard against depth-charging, but no attack materialized. The radar just wasn’t functioning.
During the night of the 20th, at the entrance to the Bungo Channel, we got an impulse on our surface radar, and while we were estimating the course, a submarine on the surface hove in sight. It was night-time with a slight mist and bad visibility, but she looked remarkably like I-36. We made our recognition signal but there was no reply. Anyway the stranger was faster than us and soon passed out of sight. On inquiring after arrival in harbor, it turned out that it was I-36: she had had no idea of our presence.
In the meantime how had the other boats in the Kongo force fared? Submarine I-56 had made for Admiralty Island but having tried to make the approach three times, she found the enemy defenses too strong and finally returned without launching her torpedoes. Submarine I-47 penetrated safely into the Hollandia harbor entrance during daylight on the 11th. She got in while enemy patrol craft were in the midst of firing practice. She reached the launching position and launched all her torpedoes at intervals of half an hour from 4 A.M. At daylight the shore base W/T station was heard transmitting a succession of S’s which was thought to indicate a submarine attack or sighting. Consequently I-47 left on her return trip with no doubts concerning the success of the attack.
Submarine I-53 went to the Kossol Passage near Palau Island but a defect prevented one torpedo from being launched and another blew up after launching owing to a burst pipe. The remaining two torpedoes were safely launched but the results were unknown.
As for I-36 it was her second operation at Ulithi. This time she approached on an opposite course, nudged a reef but was undamaged, and safely launched her torpedoes. The results, however, were not confirmed.
I-48 was due to make an attack at Ulithi on January 20, and while it was believed that she launched her torpedoes, she failed to return to harbor.
After the war we learned that I-48 was sunk in action with U.S. destroyers off Ulithi on January 22.
Altogether, the Kongo unit achieved fourteen successful launches and suffered ten failures due to various defects, and the loss of one parent submarine. As to the actual results, these are still not clear even after the war, but according to U.S. sources, I-58’s attack on Guam accounted for the sinking of a large tanker, which lost most of its crew.{23}
The poor results achieved by the antiaircraft radar during these operations led to the development of an eight-section antenna. I-58’s long life was in no small measure due to these improvements.