Japanese submarine I-55 (1943)

The Type C3 submarines were derived from the earlier C2 sub-class although with fewer torpedo tubes, an additional deck gun, and less-powerful engines to extend their range. They displaced 2,605 tonnes (2,564 long tons) surfaced and 3,702 tonnes (3,644 long tons) submerged. The submarines were 108.7 meters (356 ft 8 in) long, had a beam of 9.3 meters (30 ft 6 in) and a draft of 5.1 meters (16 ft 9 in). They had a diving depth of 100 meters (330 ft).[1]

For surface running, the boats were powered by two 2,350-brake-horsepower (1,752 kW) diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 600-horsepower (447 kW) electric motor. They could reach 17.7 knots (32.8 km/h; 20.4 mph) on the surface and 6.5 knots (12.0 km/h; 7.5 mph) underwater.[2] On the surface, the C3s had a range of 27,000 nautical miles (50,000 km; 31,000 mi) at 12 knots (22 km/h; 14 mph); submerged, they had a range of 105 nmi (194 km; 121 mi) at 3 knots (5.6 km/h; 3.5 mph).[3]

The boats were armed with six internal bow 53.3 cm (21.0 in) torpedo tubes and carried a total of 19 torpedoes. They were also armed with two 140 mm (5.5 in)/40 deck guns and one twin mount for 25 mm (1 in) Type 96 anti-aircraft guns.[3]

Ordered under the Additional Naval Armaments Supplement Programme and built at Kure Navy Yard at Kure, Japan, I-55 was laid down on 15 June 1942 with the name Submarine No. 628.[4] On 1 November 1942, she was provisionally attached to the Kure Naval District and numbered I-55;[4] she was the second Japanese submarine of that number, the first I-55 having been renumbered I-155 on 20 May 1942.[5] Launched on 20 April 1943,[4] she was completed and commissioned one year later, on 20 April 1944.[4]

Upon commissioning, I-55 was based in the Kure Naval District and assigned to Submarine Squadron 11 in the 6th Fleet.[4] In late June 1944, she was selected for conversion to carry Special Naval Weapon No. 8, a version of the Fu-Go balloon bomb that could be launched at sea, the conversion involving the installation of hydrogen and balloon-launching equipment.[4] Meanwhile, however, the Combined Fleet had activated Operation A-Go for the defense of the Mariana Islands on 13 June 1944, and the Marianas campaign had begun with the U.S. invasion of Saipan on 15 June.[4] Before her conversion could begin, I-55 got underway from Kure on 30 June 1944,[4] called at Yokosuka from 1 to 6 July 1944,[4] and then departed for Guam towing an Unpoto gun container,[4] a 70-foot (21.3 m) sled that could carry up to 15 tons of cargo, usually in the form of three Type 96 15-centimeter (5.9 in) howitzers and ammunition for them.[6]

While she was at sea on 10 July 1944, I-55 was reassigned to Submarine Division 15 in the Advance Force,[4] and on 13 July she received orders to abort her supply mission to Guam and proceed to Tinian to rescue the staff of the 1st Air Fleet there.[4] She cast the Unpoto container adrift[4] and headed for Tinian. At 00:40 Japan Standard Time on 13 July, she transmitted a message to 6th Fleet Headquarters estimating that she would arrive off Tinian on 15 July.[4] The Japanese never heard from her again.

At 21:20 on 13 July 1944, an American patrol plane spotted a Japanese submarine submerging in the Philippine Sea 78 nautical miles (144 km; 90 mi) off Saipan′s Rorogattan Point.[4] The submarine′s position was reported to a United States Navy hunter-killer group, which detached the high-speed transport USS Gilmer (APD-11) and destroyer escort USS William C. Miller (DE-259) to hunt it down.[4] The two ships arrived at the submarine′s last reported position at 00:22 on 14 July 1944 and began their search.[4] Seven hours later, William C. Miller picked up a sound contact at a range of 1,700 yards (1,600 m) and approached the contact at 15 knots (28 km/h; 17 mph). She began her attack at 07:26 by dropping a pattern of 13 depth charges, followed by a second pattern of 13 depth charges at 07:52. At 0804, her crew observed pieces of wood rising to the surface about 500 yards (460 m) ahead on William C. Miller′s starboard bow, then heard a heavy underwater explosion at 08:05 that shook the ship, followed by bubbles rising to the surface that made the water appear to boil.[4] William C. Miller dropped a third pattern of 13 depth charges at 0806, sinking the submarine.[4] An oil slick and debris covered the surface, and William C. Miller steamed into the slick and recovered pieces of cork insulating material, splintered wooden decking, and a seaman's cap at 15°18′N 144°26′E.[4]

It remains a matter of dispute as to whether William C. Miller sank I-55 or the submarine Ro-48.[4] The destroyer escorts USS Wyman (DE-38) and USS Reynolds (DE-42) also have received credit for sinking I-55 in an antisubmarine action on 28 July 1944.[7][8]

On 15 July 1944, the Imperial Japanese Navy declared I-55 to be presumed lost with all 112 hands off Tinian.[4] She was stricken from the Navy list on 10 October 1944.[4]

• Bagnasco, Erminio (1977). Submarines of World War Two. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-962-6.
• Boyd, Carl & Yoshida, Akikiko (2002). The Japanese Submarine Force and World War II. Annapolis, Maryland: Naval Institute Press. ISBN 1-55750-015-0.
• Carpenter, Dorr B. & Polmar, Norman (1986). Submarines of the Imperial Japanese Navy 1904–1945. London: Conway Maritime Press. ISBN 0-85177-396-6.
• Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press. ISBN 0-85177-146-7.
• Hashimoto, Mochitsura (1954). Sunk: The Story of the Japanese Submarine Fleet 1942 – 1945. Colegrave, E.H.M. (translator). London: Cassell and Company. ASIN B000QSM3L0.
• Stille, Mark (2007). Imperial Japanese Navy Submarines 1941-45. New Vanguard. 135. Botley, Oxford, UK: Osprey Publishing. ISBN 978-1-84603-090-1.

• Tabular movements of submarine I-55
• warsailors.com