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| Type C submarine (IJN) | |
|---|---|
| Name | Type C submarine (IJN) |
| Country | Empire of Japan |
| Type | Cruiser submarine |
| In service | 1940–1945 |
| Used by | Imperial Japanese Navy |
| Wars | Second Sino-Japanese War, Pacific War |
| Displacement | 2,564 t surfaced / 3,654 t submerged (Type C1) |
| Length | 109.3 m |
| Beam | 9.1 m |
| Draught | 5.3 m |
| Speed | 23.6 kn surfaced / 8 kn submerged |
| Test depth | 100 m |
| Complement | 95–120 |
| Armament | 8 × 533 mm torpedo tubes, 1 × 140 mm deck gun, 2–3 × 25 mm AA |
Type C submarine (IJN) was a class of cruiser submarines built for the Imperial Japanese Navy in the late 1930s and employed through the Pacific War. Designed as long-range attack and commerce-raiding platforms, the Type C combined heavy torpedo armament with extended endurance to operate across the Indian Ocean, Pacific Ocean, and waters around the Aleutian Islands. Several boats were later converted for special missions, including transport, kaiten and reconnaissance roles, and saw action in major naval campaigns such as the Guadalcanal Campaign and the Battle of Midway's aftermath.
The Type C lineage evolved from the earlier I-boat designs and the preceding Kaidai-class submarine development studies under the Sino-Japanese War era expansion of the Imperial Japanese Navy General Staff. Influenced by lessons from operations in the Second Sino-Japanese War and observations of Royal Navy and United States Navy long-range submarine practices, designers under the Navy Technical Department prioritized range, surface speed and torpedo load to counter the United States Pacific Fleet and disrupt Allied] supply lines. The design incorporated improvements from the Type B submarine (IJN) series, adopting larger fuel stowage, strengthened hull sections derived from Kaidai experiments, and a revised internal arrangement to carry additional Type 95 torpedoes compatible with IJN torpedo doctrine.
Type C boats typically displaced about 2,500–2,700 tonnes surfaced and 3,400–3,700 tonnes submerged, with an overall length near 109 metres, beam around 9 metres and draught near 5 metres—dimensions reflecting comparisons with contemporary USS Gato-class submarine and Royal Navy T-class submarine tonnages. Propulsion comprised twin diesel engines charging battery banks for electric motors, achieving maximum surface speeds exceeding 22 knots and submerged speeds near 8 knots; endurance figures allowed transits between Japan and the Indian Ocean without frequent refueling. Armament centered on eight 533 mm bow torpedo tubes with stowage for multiple Type 95 oxygen-fuelled torpedoes, supplemented by a 140 mm deck gun and light anti-aircraft mounts such as the 25 mm Type 96, paralleling IJN destroyer gun calibres. Sensors included hydrophones and a periscope suite produced by Kure Naval Arsenal standards; later boats received radar and sonar upgrades influenced by captured Allied equipment and wartime retrofits.
Type C submarines entered service as Japan expanded submarine patrols during the opening campaigns of the Pacific War, conducting patrols in the Philippine Sea, East China Sea, South China Sea, and off the Aleutian Islands chain during the Aleutian Islands Campaign. Boats of the class engaged in anti-shipping actions during the Indian Ocean raid follow-on operations and undertook reconnaissance for fleet units during operations around Guadalcanal and the Solomon Islands campaign. Several Type C units attempted attacks on convoy routes to Australia and the Indian Ocean, encountering escort tactics developed by the Royal Australian Navy and Royal Navy, as well as United States Navy destroyer screens. As Allied anti-submarine warfare, including improved sonar, radar, air cover from Escort carriers and escort commanders trained in Convoy Battle of the Atlantic-inspired tactics, intensified, Type C losses mounted in 1943–1944. Conversions to transport and kaiten-carrier roles reflected strategic shifts following defeats at Midway and during the Marianas campaign.
The Type C family included subvariants such as the C1 (original cruiser type), C2 (improved endurance and internal modifications), and C3 (further adaptations for special missions). Conversions yielded transport versions modified to carry cargo and troops to isolated garrisons during the New Guinea campaign and Solomon Islands campaign, and kaiten carriers modified to launch human torpedoes during late-war Kantai Kessen inspired operations. Some boats received reconnaissance floatplane catapults in line with designs pioneered on other IJN submarine classes and concepts similar to those used by I-400-class submarine development, though scale and implementation differed.
Construction was undertaken at major yards including Kure Naval Arsenal, Sasebo Naval Arsenal, Yokosuka Naval Arsenal, and private firms under naval planning overseen by the Navy Ministry. Keel laying and commissioning spanned 1939–1943, reflecting Japan's prewar naval expansion and wartime shipbuilding priorities that also produced Akagi (aircraft carrier) and Yamato (battleship). Deployments were assigned to fleet and local submarine squadrons operating out of bases such as Truk, Rabaul, Saipan, and home ports at Kure, Hiroshima and Yokosuka. Wartime attrition and shifting strategic needs curtailed construction plans; several ordered hulls were cancelled or repurposed as the United States Twentieth Air Force bombing campaign and blockade constrained Japanese industrial capacity.
No Type C submarine survives as a preserved vessel; most were lost in action to depth charge attacks, aircraft-delivered ordnance from B-24 Liberator and B-17 Flying Fortress patrols, or surface engagements with destroyers and escort ships. Known wrecks lie scattered across the Pacific Ocean, the Philippine Sea, the South China Sea, and waters near New Guinea; several have been identified by modern underwater archaeology efforts collaborating with institutions such as naval history museums and maritime research teams using side-scan sonar and ROV surveys. Efforts to locate and document these wrecks have intersected with broader projects examining World War II naval losses and the cultural heritage of sunken warships.
Category:Submarines of the Imperial Japanese Navy Category:World War II submarines of Japan