page_title: Kaiten
section_title: Sinking of USS Underhill
hierarchical_section_title: Kaiten / Effectiveness / Deployments / Ninth / Sinking of USS Underhill
caption_attribution_description: English: The U.S. Navy destryer escort USS Underhill (DE-682) underway, circa in late 1943.
context_page_description: Kaiten were manned torpedoes and suicide craft, used by the Imperial Japanese Navy in the final stages of World War II.
context_section_description: Arguably the most successful attack by Kaiten was that on USS Underhill commenced on 24 July 1945. She was a unit of the numerous Buckley class destroyer escort and at the time of sinking was escorting several supply and troop ships. Subsequent to being spotted by a Japanese naval reconnaissance plane; submarine I-53 attached to the Tamon group and carrying six Kaiten was redirected to the expected location of the convoy.
  The submarine launched a decoy mine ahead of the convoy's position causing the convoy to shift bearing to avoid the mine. This, however, was just diversionary and the mine was a dummy. USS Underhill after realising this noticed several sonar contacts, which were later revealed to be a Japanese submarine and several Kaiten. A depth charge run was made which did not succeed in killing the submarine although it is suspected that it did succeed in neutralizing one of the Kaiten. The depth charge run was followed by a ramming attempt on a submarine at periscope depth.
  As the Underhill rammed the surfaced vessel (later revealed to be a Kaiten) it was struck by a second Kaiten waiting in ambush. Both pilots detonated their charges, one of which led to the detonation of the destroyer's boilers, which led to her being torn in half by the explosions. The sinking resulted in the loss of almost half of her complement, including most of the officers.
  One of the attacking Kaiten also attempted an attack on a cargo vessel, LST-991, but for some reason passed under the ship's keel. This may have been the same Kaiten which successfully rammed and sank the Underhill.
  Yutaka Yokota, a Kaiten pilot whose three missions were canceled due to mechanical failure, and who wrote a memoir of his kaiten experiences, witnessed the attack on the Underhill.
  Following the successful attack on the Underhill, I-53 launched a further Kaiten at an unnamed vessel 6 days later. The attack was unsuccessful. On 3 August I-53 was detected by USS Earl V. Johnson and the destroyer began a series of unsuccessful Hedgehog attacks. I-53 launched two Kaitens separated by 30 minutes, explosions were heard, and it was confirmed that the destroyer was damaged in the attack. She escaped pursuit and returned home.
  I-58 was patrolling the Guam-Leyte route on 28 July when she was forced to dive by an aircraft. A tanker and a destroyer, USS Lowry were sighted and the commander decided to attack. Two Kaiten were launched, one of which was sunk by gunfire and the other by ramming, damaging the destroyer slightly in the process. A day later, I-58 sighted USS Indianapolis and the commander, Mochitsura Hashimoto ordered two Kaiten prepared for attack. Once in firing range the commander realised it would be a waste of a Kaiten to attack such an easy target, and instead launched a spread of six Type 95 torpedoes, three of which hit, causing the cruiser to sink rapidly. On 9 August I-58 came across a convoy led by USS Salamaua and readied three of her Kaitens to attack, of which only one could be launched. This was followed by another rapidly prepared, and both made for USS Johnnie Hutchins. Although one narrowly missed the destroyer, both were destroyed by gunfire and depthcharging. The convoy searched for other submarines, but I-58 escaped. On 12 August a Kaiten was launched against USS Oak Hill and her escort USS Thomas F. Nickel. The Kaiten passed under the destroyer, then surfaced and self-detonated. A second object was spotted by the destroyer and depth charges were launched, after which an explosion occurred. Whether this was a Kaiten is unknown, as all six of I-58's weapons were accounted for, but with two failures, perhaps one was repaired and launched later.
  On 11 August I-366 attacked a convoy north of Palau. The commander attempted to launch all of the Kaiten, but two failed, and the ones that were launched didn't score a hit or even explode. Less than a week later, Japan surrendered and all submarines were ordered home, and I-366 saw no further action.
caption: USS Underhill (DE-682)
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