was a Japanese officer and a submarine commander in the Imperial Japanese Navy during World War II. He was captain of the submarine I-58, which sank the American heavy cruiser in 1945 after its delivery of parts, gun and bullet, for the first atomic weapon used in wartime, Little Boy, prior to the attack on Hiroshima.
Born in Kyoto and educated at the Imperial Japanese Naval Academy, Hashimoto volunteered for service in submarines and was aboard submarine I-24 during the attack on Pearl Harbor in 1941. Hashimoto commanded coastal patrol and training submarines off Japan for much of the war, and in 1944 took command of I-58, a submarine which was equipped to carry kaiten manned torpedoes. After a number of unsuccessful operations, under the command of Hashimoto I-58 sank Indianapolis on 30 July with two Type 95 torpedoes while on a midnight patrol.
Hashimoto's submarine then returned to Japan, one of the few Japanese submarines to survive the war. Hashimoto was called to testify on behalf of the prosecution at the court-martial of Charles B. McVay III, the commanding officer of Indianapolis, a move which was controversial at the time. He was later part of an effort to exonerate McVay, which was eventually successful. Hashimoto, whose entire family died in the atomic bombing of Hiroshima, later became a Shinto priest. He died on October 25, 2000, five days before McVay's exoneration.
Early life Mochitsura Hashimoto was born in 1909 in Kyoto, Japan the eighth of nine children and fifth son of a kannushi (Shinto priest). He attended Kyoto Third High School, a prestigious school, where he performed well. In his youth he was described as self-possessed and respectful. At the behest of his father, he applied for the Imperial Japanese Naval Academy. The family did not have a naval background, but Hashimoto's father struggled financially on a priest's government subsidy and felt entering his son into the military would help to provide for them. One of Hashimoto's older brothers subsequently attended the Imperial Japanese Army Academy and was commissioned into the Imperial Japanese Army. Hashimoto graduated from high school in 1927 and was accepted into the Naval Academy. Leaving home for the first time, Hashimoto then attended the Imperial Japanese Naval Academy at Etajima for four years, studying Japanese history, engineering, and naval tactics, as well as judo and other military athletics. He graduated and commissioned in 1931.
In 1937, Hashimoto married Nobuko Miki, the daughter of a successful Osaka businessman. The couple had three sons; Mochihiro, born in 1940, Nobutake, born in 1942, and Tomoyuki, born in 1944;and Sonoe, a daughter born in 1947.
Military career In 1934, Hashimoto volunteered for the submarine service, and in 1937, he served aboard destroyers and submarine chasers off the shores of the Republic of China. On 15 November, as a sub-lieutenant, Hashimoto was assigned to the crew of the gunboat Hozu, and was promoted to lieutenant on 1 December.Naval appointment dated 15 November 1937, supplement to publication No. 91. Japan Center for Asian Historical Records, reference code C13072072500 (jp)Naval appointment dated 1 December 1937, Publication supplement, Japan Center for Asian Historical Records, reference code C13072072500 (jp) During that time, his brother was killed in action fighting on the Chinese mainland.
In 1938, he was assigned to the destroyer Okikaze on 15 December.Naval appointment dated 15 December 1938, supplement to publication (limited access) No. 273, Japan Center for Asian Historical Records, reference code C13072074800 (jp) Selected for submarine school the following year, Hashimoto was assigned to the Yokosuka Naval District on 20 May 1939 and enrolled in a six-month torpedo course on 1 June, subsequently entering the naval submarine school as a Class B student on 1 December.Naval appointment dated 20 May 1939, Publication (limited access) No. 338, Japan Center for Asian Historical Records, reference code C13072075700 (jp)Naval appointment dated 1 June 1939, Publication (limited access) No. 342, Japan Center for Asian Historical Records, reference code C13072075900 (jp)Naval appointment dated 1 December 1939, Publication (limited access) No. 408, Japan Center for Asian Historical Records, reference code C13072077100 (jp) Upon completion of this training, he was assigned to the submarine I-123 on 20 March 1940 as torpedo officer, transferring to the I-155 on 15 October in the same role.Naval appointment dated 20 March 1940, Publication (limited access) No. 453, Japan Center for Asian Historical Records, reference code C13072077800 (jp)Naval appointment dated 15 October 1940, Publication (limited access) No. 543, Japan Center for Asian Historical Records, reference code C13072079100 (jp)
On 15 July 1941, he was assigned to the submarine I-24, becoming its torpedo officer on 31 October, under Lieutenant Commander Hiroshi Hanabusa; the ship was based out of Kure.Naval appointment dated 15 July 1941, Publication (limited access) No. 673, Japan Center for Asian Historical Records, reference code C13072081600 (jp)Naval appointment dated 31 October 1941, Publication (limited access) No. 736, Japan Center for Asian Historical Records, reference code C13072082900 (jp) Throughout the year, the submarine conducted training maneuvers with a group of midget submarines. On 18 November, I-24 and her group sailed from Kure with a midget submarine attached to her afterdeck. Steaming eastward, she surfaced off Waikiki on 6 December. The sub was a part of a large group of submarines which would support the Attack on Pearl Harbor. Hashimoto witnessed the final ritual of Kazuo Sakamaki and Kyoji Inagaki, who would man the midget submarine, which cast off at 05:30. I-24 remained at a rendezvous point to wait for the midget sub, which never came. On 9 December, I-24 steamed for Kure.
Upon the submarine's return to Kure, Hashimoto was detached and assigned to the advanced course at Submarine School on 1 February 1942, to prepare him for command of a submarine.Naval appointment dated 2 February 1942, Publication (limited access) No. 805, Japan Center for Asian Historical Records, reference code C13072084200 (jp) Graduating from this course on 30 June, Hashimoto was given command of submarine Ro-31, a coastal defense vessel. For the remainder of 1942, Hashimoto operated his ship in home waters off Yokosuka training crews and trying new equipment and doing research for the development of Japanese submarine doctrine. He was promoted to lieutenant commander on 1 November.Naval appointment dated 1 November 1942, Publication (limited access) No. 974, Japan Center for Asian Historical Records, reference code C13072087700 (jp) In 1943, he was given command of submarine I-158 for coastal defense, and later in the year was given command of submarine Ro-44 for the same duties.
Commanding I-58 In May 1944, Lieutenant Commander Hashimoto was given command of submarine I-58 which was still under construction in Sasebo. Hashimoto oversaw much of the construction of I-58. The submarine was later overhauled mid-construction to carry Kaiten manned torpedoes, which was considered a great honor by Hashimoto's crew. I-58 was commissioned on 13 September 1944 and Hashimoto commanded her during her shakedown cruises, commanding his men on repeated drills without shore leave. He completed training on the submarine in December 1944. The ship traversed Shimonoseki Strait into the Inland Sea and to Kure for supplies. She then moved to Hirao where she loaded six kaitens.
On 29 December, she left on her first war patrol, steaming for the Mariana Islands. She arrived off the coast of Guam at 03:00 on 11 January 1945 and Hashimoto ordered four kaitens launched. The kaitens tentatively claimed a tanker sunk, though it was unable to verify if the ship had actually been struck. The strike had been unsuccessful. She then sped back to Kure and arrived there on 20 January. She remained in port there until March, likely due to supply shortages. On 1 March, she was ordered to Iwo Jima to support the battle taking place there. Once there, I-58 was ordered to launch all of its kaitens without their pilots and immediately return home. She was ordered out again on 2 April sailing to support Japanese forces at the Battle of Okinawa. While there, she was attacked by aircraft 50 times. She never surfaced for more than a few hours. She limped to Kure on 29 April 1945, the only Japanese submarine to withdraw from the operation. She remained in port because of continued mining conducted by U.S. Army Air Forces, and departed on 16 July on another war patrol. At the time, she was one of only four large submarines left in the Japanese Navy, and her mission was to harass Allied lines of communications.
Passing through the Inland Sea around minefields, I-58 headed for the east coast of the Philippines intending to attack ships there. Passing east of Okinawa and spotting no ships, she cruised south arriving at the Guam-Leyte shipping lane on 27 July. She spotted a tanker escorted by a destroyer and Hashimoto ordered her to launch two kaitens at 14:31 and 14:43. She heard explosions at 15:21 and 15:31 but her crew was unable to determine if the kaitens had struck their targets. Hashimoto reported a tanker assumed sunk.
Sinking of Indianapolis On 29 July, Lt. Cmdr. Hashimoto ordered the submarine to make for an area where he believed shipping lanes between Guam, Leyte, Peleliu and Okinawa intersected. At 23:35 that evening, Hashimoto spotted the heavy cruiser at cruising for his position at medium speed. Believing the ship to be an "Idaho-class" battleship, he ordered I-58 to dive and once Indianapolis closed to he ordered six regular torpedoes fired at 00:02 on 30 July. Spotting three explosions strike the Indianapolis, Hashimoto ordered the submarine on a deep dive fearing detection. After an hour at a deep dive to reload, she surfaced and did not spot Indianapolis. After searching unsuccessfully for flotsam or any sign of the ship, he ordered the I-58 to retire at 02:30. He transmitted a short wave radio message to the 6th Fleet headquarters in Kure at about 03:00 noting the destruction of the ship. He later wrote of the incident:
Hashimoto ordered I-58 northward looking for additional ships to attack. She picked up reports of the atomic bombing of Hiroshima in intercepted radio transmissions on 7 August but Hashimoto continued to hunt for Allied ships south of Bungo Strait. On 9 August she launched two kaitens against a convoy, and Hashimoto claimed a destroyer probably sunk. On 12 August he launched his remaining kaitens and claimed a merchant ship probably sunk. I-58 surfaced in Bungo Strait on 15 August, where Hashimoto learned of the Gyokuon-hōsō signaling the Japanese surrender and end of the war. She traveled up the Inland Sea and arrived at Hirao where Hashimoto emotionally informed his crew of the end of the war. After the war, it was confirmed Indianapolis was the only ship I-58 had sunk. It was the last Japanese naval success of World War II. When Hashimoto came home from the war, he learned that his entire family had been killed in the atomic bombing of Hiroshima on 7 August.
McVay court-martial