Japanese submarine I-46

Upon commissioning, I-46 formally was attached to the Yokosuka Naval District and assigned to Submarine Squadron 11 for shakedown and work-ups.^[4] During a training sortie in the Iyo-nada on 2 April 1944, she collided underwater with the submarine Ro-46 off Minase Bight southwest of Kominasa Light at 21:45, suffering damage to her conning tower and periscopes.^[4] After repairs and testing, she arrived at the Sasebo Naval Arsenal on 7 May 1944 for additional repairs.^[4]

I-46 was reassigned to Submarine Division 15 in the 6th Fleet on 30 May 1944.^[4] On 12 August 1944, her commanding officer submitted a memorandum to the headquarters of the 6th Fleet and the commander of Submarine Squadron 11 suggesting improvements to the Type 13 air search radar installation and application of the anti-radar coating aboard I-46.^[4]

On 13 October 1944, the Combined Fleet ordered the activation of Operation Shō-Gō 1, the defense of the Philippine Islands, in anticipation of an American invasion of the islands.^[4] I-46 departed Kure, Japan, to begin her first war patrol and take part in Shō-Gō 1, assigned a patrol area 120 nautical miles (220 km; 140 mi) east of Leyte in the Philippines as part of the "B" Group.^[4] Her patrol area was the westernmost of those assigned to the submarines of her group, and was adjacent to the area assigned to the submarine I-54.^[4]

On 20 October 1944, the Battle of Leyte began with U.S. landings on Leyte.^[4] In response, major units of the Imperial Japanese Navy converged on Leyte, resulting in the Battle of Leyte Gulf, which lasted from 23 to 26 October 1944.^[4] On 24 October, the 6th Fleet ordered eleven submarines, including I-46, to converge in an area extending from Samar to Surigao Strait.^[4]

While I-46 was operating east of Leyte on 25 October 1944, a U.S. patrol plane forced her to dive at 06:45.^[4] A ship she identified from its propeller noises as a destroyer pursued her for the next eleven hours, during which she heard over 200 distant depth charge explosions.^[4]

On 26 October 1944, I-46 transmitted a report that she had sighted a small Allied convoy east of her patrol area.^[4] She was never heard from again.^[4] When the 6th Fleet ordered her to move to a new patrol station east of Leyte on 27 October 1944, she did not acknowledge the order.^[4]

The circumstances of I-46′s loss remain unknown.^[4] At 12:18 on 28 October 1944, the destroyers USS Gridley (DD-380) and USS Helm (DD-388) detected a submarine attempting to penetrate the screen of United States Navy Task Group 38.4 — which included the aircraft carriers USS Enterprise (CV-6), USS Franklin (CV-13), USS Belleau Wood (CVL-24), and USS San Jacinto (CVL-30) — east of Leyte.^[4] While the aircraft carriers steered away from the submarine contact at high speed, Gridley made three depth charge attacks against the submarine and Helm made four.^[4] After Helm′s fourth attack, which took place at 14:11, a large explosion followed by two smaller ones occurred.^[4] Oil and air bubbles appeared on the surface, and damaged deck planking and human remains were recovered after the attack.^[4] The submarine sank at 10°58′N 127°13′E / 10.967°N 127.217°E / 10.967; 127.217.^[4]

On both 30 October and 1 November 1944, I-26, I-46, and I-54 all failed to make scheduled daily 19:00 status reports.^[4] On 2 December 1944, the Imperial Japanese Navy declared I-46 to be presumed lost east of the Philippines with the loss of all 112 men on board. She was stricken from the Navy list on 10 March 1945.^[4]

The identity of the submarine Gridley and Helm sank remains a mystery, and has been reported both as I-46 and I-54.^[4] In 1976, it also was suggested that the destroyer escort USS Lawrence C. Taylor (DE-415) sank I-46 in the Philippine Sea east of Samar on 18 November 1944, although the submarine Lawrence C. Taylor sank probably was I-41.^[4][5] Some historians have claimed that a submarine the destroyers USS Saufley (DD-465), USS Waller (DD-466), USS Pringle (DD-477), and USS Renshaw (DD-499) sank in the Ormoc Bay area on 28 November 1944 was I-46, but by then I-46 had been missing for over a month, and they most likely sank Yu 2.^[6]

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• Boyd, Carl & Yoshida, Akikiko (2002). The Japanese Submarine Force and World War II. Annapolis, Maryland: Naval Institute Press. ISBN 1-55750-015-0.
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• Stille, Mark (2007). Imperial Japanese Navy Submarines 1941-45. New Vanguard. Vol. 135. Botley, Oxford, UK: Osprey Publishing. ISBN 978-1-84603-090-1.