Here, I-37's part in the mission that departed Japan on November 9 came to a premature end. Shortly before 0900 on 19 November, I-37 surfaced briefly at the western entrance to Kossol Passage, where she was sighted by net-layer USS Winterberry, (AN-56). Winterberry was laying a torpedo net across the West entrance to Kossol Passge when she sighted a surfaced submarine, distance 2500 yards, at 0858. Lt. Cmdr. S.E. Aarens sent an urgent message to the port commander and also to YMS-33 stationed as a listening watch at the west entrance. Winterberry was ordered to investigate the contact. I-37 seemed to disappear and then surfaced again twenty seconds later. The I-class submarine seemed to surface with a steep angle with the bow approaching the vertical.

The commander of Task Group 57.6 ordered USS Conklin, (DE-439) and USS McCoy Reynolds, (DE-440), underway at 0915 forming a hunter-killer group to destroy I-37. Lt. Cmdr. E.K. Winn commanding McCoy Reynolds was named Officer in Tactical Command (OTC). Navy planes were dispatched from Peleliu to assist in the hunt. The Conklin and McCoy Reynolds paired for a retiring box search. The two ships were parallel, 3000 yards apart, pinging a 180 degree sonar arc beam to beam. Howard Higgins, Y3c, was the helmsman aboard Conklin. Captain Edmund L. McGibbon paced the bridge as Conklin searched for the target. "The Captain was on my ass every minute" complained Higgins. "Go this way, go that way!"

The crews of both destroyer escorts had now been at General Quarters for 6 hours when sonar operators aboard McCoy Reynolds and Conklin sang out at 1504. "Sound contact, range 1600 yards, course 130 degrees T! Change course to 130 degrees, 10 knots, ordered Conklin’s skipper. Conklin was ordered to stand by while McCoy Reynolds initiated a hedgehog attack. Higgins gripped the wheel of Conklin as the Captain ordered course changes quickly to retain sonar contact with the target. McCoy Reynolds fired hedgehogs at 1539 and a second attack shortly after, both unsuccessful. I-37 by this time had dived to a depth of 350 feet. McCoy Reynolds pressed the attack with 13 depth charges and soon lost contact with I-37 as underwater depth charge explosions obliterated the sonar echoes.

The crew of Conklin wondered if their ship would be next to attack. They did not have to wait long. "Contact!" The sonar operator aboard Conklin had re-located I-37 at 1603 and Captain Brown ordered a hedgehog attack at 1615. Within a minute, Conklin’s sonar operator heard an explosion deep below. A hedgehog would not explode unless contact was made with the hull of a submarine. The Conklin had found her mark!

A massive underwater explosion was felt by the sailors aboard Conklin and McCoy Reynolds at 1700, almost 8 hours since the search for I-37 had started. Minutes after this explosion, a huge air bubble rose to the surface of the ocean. Kaiten carried large oxygen tanks for submergence and steering. Perhaps these kaiten, and their air tanks, exposed to the hedgehog explosions, contributed to the massive air bubble. Topside personnel aboard Conklin spotted fuel oil, cork, decking, and pieces of finished wood including bits of human flesh in the middle of the expanding oil slick.

Captain McGibbon had no way of knowing that Conklin, had very likely touched off the explosive power of the combined warheads of four Japanese kaiten. The total high explosive was 13, 672 lbs! Admiral William, "Bull" Halsey, commander Third Fleet sent a message to the successful hunter-killer team Conklin and Reynolds. "Well done on your job of recruiting for the Association of Nip Ancestors."

Kikusui Group Attack on Ulithi

I-36 and I-47 reached their launching area off Ulithi without incident. Lt. Cmdr. Zenji Orita, I-47, was in overall command of the Kikusui mission. On November 16, a few days before the attack, a high-attitude reconnaissance aircraft from Truk reported that Ulithi lagoon was crammed with shipping, including aircraft carriers and battleships. US Navy warships were located in the north central part of the lagoon. The south central part of the anchorage was occupied by transports, oilers and other auxiliary vessels. The intelligence, relayed to the submarines from Japan, was good: present at the time of the attack were the four fleet carriers, three battleships, cruisers and destroyers of Rear-Admiral Frederick Sherman's Task Group 38.3; the heavy cruisers and destroyers of Task Group 57.9; a number of major and minor units under repair; and the many fleet auxiliaries of Commodore W.R. Carter's Service Squadron 10 -- perhaps some 200 ships in all.

Lt-Cmdr. Zenji Orita, in I-47, surfaced at sunset November 18, fifty miles west of Ulithi to check the condition of the kaiten. The kaiten were fastened to the deck using clamp rings and blocks of wood. Maintenance men aboard I-47 loosened the first and fourth hold-down band on each 48' manned torpedo, leaving only the two center bands to be released from inside the submarine at launch time. All kaiten were found to be in good shape for the attack on Ulithi.

Captain Orita submerged I-47 one hour before sunrise on the morning of November 19 and stabilized I-47 at 180' below the surface to avoid US patrol planes. I-47 crept to within four miles west of Eau and Ealil Islands on the west side of Ulithi. Orita brought I-47 to periscope depth and raised his periscope and made a quick sweeping look at 0930 calling out the bearings of three cruisers inside Ulithi to his navigator. I-47 dived and came to periscope depth again just before noon. Orita raised his periscope 4' above the water to get a good look at Ulithi. The nearest cruiser was only 3 miles away!

Orita could see several cruisers beyond the nearest U.S. Navy ship along with battleships. Aircraft carriers were located beyond that with patrol planes seen circling above the ships. All of these ships were located towards the south and southwest area of Ulithi. Orita could see ships in the central part of the harbor, moored in rows. Thin rising columns of smoke marked the presence of other U.S. ships beyond what Orita could see.

"Here Nishina," Captain Orita said to the kaiten co-inventor, "take a look." Nishina peered into the periscope for two long minutes as he strained to see as much as possible and drawing his breath in slowly. Abruptly, he said, OK! relinquishing the periscope to Sub-Lt. Fukuda. Ensigns Sato, and Watanabe next took their turns at the periscope of I-47. The pilots were elated at what they saw. Nishina commented in his diary for the day on the "golden opportunity to use kaiten."

Cmdr. Iawo Teramoto, in I-36, was scouting northeast of Ulithi searching for the entrance to Mugai channel. Imanishi, Kudo, Yoshimoto, and Toyozumi impatiently waited for the opportunity to board their weapons the next day.

I-47 Launches Kaiten

The four kaiten pilots accepted a gift from I-47's Chief Oka after writing their last words each wanted to leave behind. Oka had produced a sketch he had been working on in soft lead pencil in varying shades. It showed an American aircraft carrier breaking in two as a kaiten struck it. All four pilots autographed it and Nishina wrote "Gochin" meaning "instantly sunk" under his signature. That evening, at dinner, a fine sake, a gift from the Emperor, was served in lacquer-ware cups. After this last dinner, the kaiten pilots purified themselves with spring water, shaved and neatly trimmed their hair. Sub-Lt. Nishina did not shave or cut his long hair, stating "I will not shave or cut my hair until I have obtained my hit against a U.S. ship!" The four pilots retired to their cabins to rest and Orita approached Ulithi on the surface at 12 knots charging the batteries of I-47.

Sub-Lt. Sekio Nishina wrote in his diary:

"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 regrettable matter."

Ensigns Akira Sato and Kozo Watanabe emerged on the bridge of I-47, white hachmaki headbands adorned the young pilot’s heads. The pair entered the open hatches of kaitens #3 and #4 secured on deck, while I-47 risked detection on the surface from US Navy anti-submarine patrols. There were no access tubes from I-47's main deck leading to Sato and Watanabe's craft. The technicians tended to the kaiten, helping Sato and Kozo enter their craft. The men tightened the bolts of the hatches to prevent leaks and then collapsed sobbing underneath the kaiten. Orita could see the sparkles of welding torches inside Ulithi as the US Navy repaired battle damaged ships. The time was 1:00AM on November 20 and I-47 was about 12 miles from the launch point. I-47 slipped beneath the surface of the ocean as Orita submerged with Sato and Watanabe sealed inside their kaiten. The crew of I-47 became somber as they thought of the brave young men who now waited in their steel coffins for their deaths.

Sub-Lt Nishina slowly saluted Orita and the men of I-47 with a small white box containing the ashes of his kaiten co-inventor friend Kuroki in his hand. Kuroki had died in a kaiten training accident at Otsujima base on September 6. Nishina spoke softly to Captain Orita "I am much obliged to you. Thank you very much." At 3:00AM, Sekio Nishina, co-inventor of the kaiten, entered his weapon crawling through an access tube to his kaiten #1, soon to be the first to launch.

Nishina thanked the crew of I-47 and Captain Orita for getting so close to the enemy without detection. "Please do not endanger your ship in observing our results Sir" he said. Kaiten operations should always remain a mystery to the enemy, if possible." Nishina had hoped I-47 would leave the area quickly so that the Americans would have difficulty pin pointing the source of the attack.

"They are acting as if everything is routine. Death is only minutes away!" Orita thought to himself. "Orita was troubled by the turn of events and the decision by Japanese 6th Fleet command under Admiral Miwa, to resort to the use of tokko or suicide weapons. The thought of life versus death had rarely left Orita since learning about the proposed use of kaiten. "Things must really be bad, if we have to resort to this!"

All four kaiten were successfully launched from I-47: Nishina at 4:15AM; Sato at 4:20; Watanabe at 4:25; Fukuda at 4:30. Each was to pursue a different attacking course, in order to strike targets in widely separated locations within the lagoon at approximately 5:00AM.

I-36 Launches Kaiten

Aboard I-36, things did not go so smoothly for Cdr. Iwao Teramoto. When I-36 surfaced, Ens. Taichi Imanishi and Ens. Yoshimoto Kudo boarded their kaiten. Hours later, at 3 A.M., Lt. Kentaro Yoshimoto and Lt. Kazuhisa Toyozumi crawled into the other kaiten via access tubes.

Teramoto had his submarine 9.5 miles from Mas Island (which marks the right-hand side of Mugai Channel) at 4 A.M. The approximate position would be in a southeast direction from Mas Island close to the entrance to Mugai channel. The anti-submarine net that guarded the entrance to Ulithi was positioned southwest to northeast beginning about one mile northeast of Mangejang Island and Mugai channel.

At that time, about 4AM, Cmdr. Teramoto discovered that kaiten #1,# 2 and #4 had jammed in their racks and could not be fired. The engines of the first two kaiten were started and the weapons were found to be immovably wedged on their chocks. A third kaiten failed to start: seawater had leaked into its propulsion mechanism.

Only one kaiten, that piloted by Ensign Taichi Imanishi, got away -- at 4:54AM. Ensign Imanishi headed in the direction of just West of Mas Island in an attempt to penetrate the anti-submarine torpedo net targeting the fleet carriers and battleships in the northeast part of the lagoon.

Kaiten Attack

Control of the kaiten weapon was difficult. The pilots had the ability to penetrate Ulithi lagoon at 20-30 knots, while juggling their controls in order to stay at the optimum depth of 15 feet, a very difficult task under the best of conditions. The pilots, with only two months training, operating diving planes and rudder controls, manipulated the valve that admitted sea water to compensate for the fuel used, and checked the gyro-compass and stop-watch to hold the predetermined attack course.

To avoid detection, and probable destruction from enemy guns, the periscope should not be raised until an estimated 15 seconds before impact. At that time, the kaiten should be making its final run in to the target at its maximum speed of 30 knots, and only slight rudder corrections should be necessary to ensure a direct hit amidships.

This was the theory: in practice, it was unlikely that the directions given by I-47's Orita or I-36's Teramoto, viewing the target area at a distance, through a periscope, in pre-sunrise darkness, would be sufficiently accurate to enable the kaiten pilot to steer to a predetermined target without visual reference. At Ulithi, the kaiten pilot’s opportunity for a target diminished as they found navigation into unfamiliar channels in pre-sunrise darkness, an almost impossible task.

As US combat reports reveal, the kaiten pilot, having reached the vicinity of enemy ships, often was forced to reveal his presence by raising his periscope to seek a target before beginning his final run in at maximum speed. This was the case with the I-47 launched kaiten spotted and rammed by the USS Case at 5:38AM. Ens. Imanishi, launched from I-36 penetrated the lagoon West of Mas Island and was spotted by a lookout aboard light cruiser USS Mobile.

The fact that two kaiten during the "Kikusui" mission were sunk hours after their release indicated that a pre-sunrise launch in darkness hampered the efforts of some of the pilots to navigate successfully. The four kaiten from Orita’s I-47 left the mother submarine a long distance from the target area. This certainly resulted in increased chances of detection or worse, becoming lost.

November 20, 1944 "Kikusui" Mission Ulithi Attack Results

Four kaiten had been released by I-47 and one kaiten released by I-36 in the pre-sunrise darkness of Monday, November 20, 1944. The results were as follows:

1) USS Sumner, (AGS-5) reported a an explosion and a large flash on a reef 1/2 mile south of Pugelug Island at 4:20AM. The remains of a Japanese kaiten washed ashore sometime in December 1944, thus alerting the US Navy to the true nature of this new Japanese suicide weapon.

2) USS Case (DD-370) rammed and sank the first kaiten discovered at 0538 approximately two miles south of Mugai channel, the large northeastern entrance to Ulithi that was the main channel used by the US Navy. The wreckage slid down the hull of Case and the kaiten was clearly observed by topside personnel.

3) USS Mississinewa (AO-59) exploded when struck by a kaiten at the southernmost berth (131) at the entrance of Mugai Channel between 5:45AM and 5:47AM as recorded in US Navy deck logs from vessels at Ulithi. Chip Lambert’s Mississinewa discovery team in April 2001 determined that the AO-59 was on a direct course and likely to be a target of kaiten co-inventor Seiko Nishina who penetrated Zau Channel in a direct line with Missisisnewa’s known position.

4) A kaiten was believed sunk by USS Rall (DE-304) at 0653 inside Ulithi harbor after the Japanese attacker was sighted by USS Mobile (CL-63). Two Japanese swimmers had been sighted in the water although they sank from sight before they could be recovered. ComServRon 10 reports refer to this incident as the second kaiten found and sunk. A Japanese body was recovered from the water in berth 23 on the morning of November 23, 1944 by LCI-602. Positive identification of the badly decomposed corpse as Japanese was made by Dr. Ecklund, Pathologist, USS Solace (AH-5). The body may have been Ens. Imanishi launched from I-36.

5) The light cruiser USS Reno, CL-96, reported an explosion and a flash on a reef two miles south of Pugelug Island at 11:32AM. The explosion was also seen by USS Sumner. The US Navy reported that a torpedo may have been fired from outside the reef. No proof of a kaiten attack was ever found and the disposition of the fifth kaiten from the "Kikisui" attack may never be known.

Commodore Walter R. Carter, ComServRon 10, clearly stated that he believed only three Japanese kaiten had penetrated Ulithi Atoll anchorage on November 20, 1944. He knew USS Case rammed and sank a kaiten two miles south of the entrance to Mugai channel. USS Rall sank a kaiten inside the harbor with two alleged Japanese swimmers spotted in the water and wreckage recovered. The body of a Japanese sailor was recovered in the harbor on November 23, 1944. Carter believed that a kaiten had been sunk 15 miles east of Falalop Island after sunset on November 20, 1944. This "sinking" reported by two patrolling US Navy "Avenger" torpedo bombers was in fact, the escaping I-36 crash diving to avoid a US Navy attack. I-36 made her way back to Japan safely. Carter believed the two large reef explosions at 0418 and 1132 south of Pugelug Island on November 20, 1944 were kaiten blowing up after striking the reef attempting to enter Zowabatu Channel.

Commodore Carter, Commander of Service Squadron 10, seemed to still be unsure of the number of kaiten attackers when his December 8, 1944 Action Report, Serial 00274 was filed. The remains of the kaiten on the reef near Pugelug Island must not have been discovered until after this December 8, 1944 Action Report. No mention was made in this Service Squadron 10 report of the recovery of Japan’s new secret weapon.

Kikusui Mission to Ulithi is a Japanese Success?

Lt. Cmdr. Zenji Orita, in I-47, remained submerged off Ulithi to the southwest near 0530 after a patrolling US destroyer forced I-47 down to 170' at a steep 15 degree down angle dive. I-47 sensed a mild shock at 0552. "Small explosion inside the lagoon!" reported the sound operator to Orita. Orita brought I-47 to periscope depth and made a quick scan of the anchorage. At 0600, Captain Orita ordered all hands to maintain one minute of silence in prayer for the kaiten pilots. I-47 swung west and headed north to attack enemy shipping in Leyte Gulf with conventional torpedoes.

The two Japanese submarine commanders observing Ulithi from seaward recorded explosions within the lagoon at 5:07, 5:11, 5:45, 5:52 and 6:05.

I-36, after releasing Ens. Imanishi at 4:54 AM dived and listened for explosions. Lt. Cmdr. Iwao Teramoto lay submerged off the northeastern entrance to Ulithi near Mugai channel. The sound equipment aboard I-36 picked up two explosions, one at 5:45 AM and one at 6:05AM. US Navy action reports from USS Mississinewa report the first explosion was a kaiten, now believed to be Sub-Lt. Seiko Nishina, from I-47. Mississinewa was anchored in the very center of Mugai channel and was the southernmost ship closest to Nishina’s Zau Channel attack path.

The second explosion heard by I-36 at 6:05 AM was reported by Captain Beck of the USS Mississinewa as a secondary explosion from the 5"/38 caliber ammunition magazine blowing up from fires spreading aft. Eyewitness accounts by Mississinewa survivors and crew members of fleet tug USS Munsee (ATF-107), tied up alongside the AO-59 to fight the raging fires, confirm the timing of these explosions.

The disappointed kaiten pilots on I-36 pressed Lt. Cmdr Teramoto to resurface at a safe distance and attempt to repair their kaiten torpedoes for a follow-up strike; but a wide-ranging depth charge hunt by US warships racing from the atoll immediately after the explosions forced I-36 to remain submerged for the rest of the day. Teramoto reported later that he was unable to surface I-36 until late on November 20 and, after recharging his batteries, began the run on the surface at flank speed, as did I-47, to begin operations in the Leyte Gulf area with conventional torpedoes.

Orita made his initial report to Japan’s Kure Naval Base by wireless on November 22. Teramoto made his wireless report to 6th Fleet command on November 23. I-47 and I-36 had their orders to Leyte Gulf canceled on November 24 and were ordered back to Japan by Admiral Miwa. Both submarines arrived at the secret kaiten training base at Otsujima, Tokuyama Bay, where I-36 delivered the three bitterly disappointed kaiten pilots back to their secret base at Otsujima Island.

I-36 and I-47 both arrived at the large Kure Naval Base on 30th November. On December 2, a special conference was held aboard Tsukushi Maru, flagship of the Sixth Fleet, to consider Orita and Teramoto's reports on the kaiten attacks. Over 200 staff officers and specialists attended this meeting to evaluate the Kikusui mission to Ulithi.

There was a lot of arguing as to whether the mission should be kept secret or announced. Orita remembered that Nishina had wanted the kaiten to be kept secret. Orita disagreed with the kaiten co-inventor. "The enemy knows about it, I am sure. What value is there to keeping it (kaiten) secret?" Orita hoped that by announcing the results of the mission, the tactic of attacking anchorages would be discarded. Air and sea patrols and anchorage nets all barred the way for kaiten to attack an anchorage. Orita knew the staff of the 6th Fleet and submarine school instructors were advocates of attacking enemy supply lines. Orita was argued down before the formal portion of the meeting had even started.

Cmdr. Shojiri Iura explained the original operational plan for the November 20 Ulithi attack. Lt. Cmdr.’s Orita and Teramoto told about the actual mission. A study and discussion followed. The conclusions of the results of the November 20, Kikusui mission were based on the two columns of fire Orita witnessed, the two explosions Teramoto reported, (these from USS Mississinewa) and periscope observations. The original kaiten attack plan was considered and aerial photos evaluated from before and after the attack. There was a lot of discussion before the results were summarized by Lt. Cmdr. Bunichi Sakamoto, 6th Fleet communications officer.

"Men on board I-47 observed two fires," he said. The crew of I-36 heard explosions. Photographs of Ulithi taken by a reconnaissance plane from Truk, on 23rd November, three days after the kaiten operation, were then produced. "From these", declared the speaker, "We can estimate that Lieutenant Nishina sunk an aircraft carrier, as did Lieutenant Fukuda and Ensign Imanishi. Ensigns Sato and Watanabe sank a battleship apiece!"

Overly optimistic accounts of success such as this attack on Admiral Halsey's Third Fleet anchorage at Ulithi Atoll plagued Japanese war planning throughout the Pacific war.
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By: Mike Mair
Copyright 2003