I-55, later renumbered , was an Imperial Japanese Navy cruiser submarine of the KD3A sub-class commissioned in 1927. Early in World War II, she supported Japanese forces in the invasion of Malaya and the Dutch East Indies campaign before assuming training duties in Japan, interrupted briefly in 1943 by her participation in the Aleutian Islands campaign. She became a kaiten manned suicide attack torpedo carrier in 1945 before surrendering at the end of the war. She was scuttled in 1946.

Background Following World War I, the Imperial Japanese Navy re-evaluated the use of submarine warfare as an element of fleet strategy due to the successful deployment of long-range cruiser submarines for commerce raiding by the Imperial German Navy. Japanese strategists came to realize possibilities for using submarines for long-range reconnaissance and in a war of attrition against an enemy fleet approaching Japan.Peatty, pp. 212–14 The Japanese already had built two large, long-range submarines — and I-52 — under the Eight-six fleet program as prototypes, but the arrival on 20 June 1919 of seven German U-boats Japan received as war reparations after the end of World War I led to a complete re-design. The Japanese quickly hired hundreds of German submarine engineers, technicians, and former U-boat officers unemployed after the defeat of the German Empire in World War I and brought them to Japan under five-year contracts. The United States Navy′s Office of Naval Intelligence estimated that some 800 German advisors had gone to Japan by the end of 1920. The Japanese also sent delegations to Germany, and were active in purchasing many patents related to submarine design and construction.Boyd, pp. 17–18

Design The four Kaidai Type 3A submarines were the first mass-produced Japanese fleet submarines. Based largely on the lone Kaidai Type II submarine (I-52), their design was also influenced by the largest of the German submarines in Japanese hands, .Stille, p. 4 Compared with I-52, they a strengthened double hull. The hull had almost the same outer dimensions as that of I-52, but the increased thickness of the inner hull permitted a diving depth of . The internal volume was slightly increased over that of I-52 by making the hull slightly trapezoidal in cross-section at the expense of 300 tons of additional displacement. External differences from I-52 included an anti-submarine net cutter on the bow, as well as an O-ring for towing purposes.

The Kaidai Type 3A submarines displaced surfaced and submerged. The submarines were long and had a beam of and a draft of . They had a complement of 60 officers and crewmen.Carpenter & Polmar, p. 93

Sulzer was retained as the manufacturer for the diesel engines, which had a slightly improved performance over the engines in I-52. For surface running, the submarines were powered by two diesel engines, each driving one propeller shaft. When submerged, each propeller was driven by a electric motor. The submarines could reach on the surface and submerged. On the surface, the KD3As had a range of at ; submerged, they had a range of at .Chesneau, p. 198

The submarines had eight internal torpedo tubes, six in the bow and two in the stern. They carried one reload for each tube for a total of 16 torpedoes. They were had one deck gun.Bagnasco, p. 183

Construction and commissioning Built by the Kure Naval Arsenal, I-55 was laid down on 1 April 1924 as . While under construction, she was renamed I-55 on 1 November 1924. She was launched on 2 September 1925 and completed and commissioned on 5 September 1927.

Service history Pre-World War II On the day she was commissioned, I-55 was assigned to the Kure Naval District and assigned to Submarine Division 18 in Submarine Squadron 2 in the 2nd Fleet, a component of the Combined Fleet. During a training exercise on 11 July 1929 in which she simulated a submerged torpedo attack against the heavy cruiser , she accidentally collided with Kinugasa off Kyushu southwest of Ōdate Shima lighthouse, sustaining substantial damage to her bow plating. On 1 December 1930, Submarine Division 18 was reassigned to the Kure Defense Squadron in the Kure Naval District.

Submarine Division 18 began a second assignment to Submarine Squadron 2 in the 2nd Fleet on 1 December 1931. At 13:48 on 10 February 1932, I-55′s sister ship I-54 suffered a steering failure off Kyushu south of Odate Shima lighthouse while Submarine Division 18 was on maneuvers during fleet exercises. I-54 reduced speed to , but nonetheless accidentally rammed I-55. I-54 suffered bow damage and one of her compartments flooded, but I-55 sustained only minor damage.

Between February 1932 and February 1934, Submarine Division 18 was active, concluding duty in Submarine Squadron 2 in the 2nd Fleet with its reassignment to the Kure Defense Division in the Kure Naval District on 15 November 1933 and then to the Kure Defense Squadron in the Kure Naval District on 11 December 1933 before it began a third tour of duty in Submarine Squadron 2 in the 2nd Fleet on 1 February 1934. I-55′s activities during this period are unclear: She may have been in reserve from the day of her collision with I-54 on 10 February 1932 until 20 February 1934, or she may have remained active in her division. In the latter case, she got underway from Sasebo on 29 June 1933 with the other submarines of her squadron (I-53 and I-54 of her division and Submarine Division 19's I-56, I-57 and I-58) for a training cruise off China and Mako in the Pescadores Islands, which the submarines concluded with their arrival at Takao, Formosa, on 5 July 1933; departing Takao on 13 July 1933 with the other five submarines and again training in Chinese waters before arriving in Tokyo Bay on 21 August 1933; and taking part with the other five submarines in a fleet review at Yokohama, Japan, on 25 August 1933. Submarine Division 18 was reassigned to the Kure Defense Division in the Kure Naval District on 15 November 1933 and then to the Kure Defense Squadron in the Kure Naval District on 11 December 1933 before it began a third tour of duty in Submarine Squadron 2 in the 2nd Fleet on 1 February 1934.

On 7 February 1935 I-55 got underway from Sasebo along with the other eight submarines of Submarine Squadron 2 — I-53, I-54, I-59, , , , and — for a training cruise in the Kuril Islands. The cruise concluded with their arrival at Sukumo Bay on 25 February 1935. The nine submarines departed Sasebo on 29 March 1935 to train in Chinese waters, returning to Sasebo on .

Submarine Division 18 was reassigned to Submarine Squadron 1 in the 1st Fleet, a component of the Combined Fleet, on 15 November 1935. While the division was on maneuvers during fleet exercises off Kyushu on 10 May 1936, I-55 collided with her sister ship I-53, sustaining minor damage to her bow plating. On 23 July 1936 I-55 suffered more extensive damage when the Combined Fleet was caught in a typhoon off Beppu, Kyushu, during fleet exercises and she ran aground in Terajima Channel, suffering severe damage to her hull plating. After her superstructure was partially dismantled, she was refloated and towed to Kure, Japan, on 31 July 1936, where she was drydocked for repairs. She was placed in reserve that day. All of Submarine Division 18 followed her into reserve at Kure on 20 August 1936.

Submarine Division 18 returned to active service on 1 October 1936, when it began another tour of duty in Submarine Squadron 1 in the 1st Fleet, and I-55 returned to active service in the division on 1 December 1936. The division was reassigned to Submarine Squadron 4 in the 1st Fleet on 15 November 1939. On 11 October 1940, I-55 was one of 98 Imperial Japanese Navy ships that gathered along with more than 500 aircraft on the Japanese coast at Yokohama Bay for an Imperial fleet review — the largest fleet review in Japanese history — in honor of the 2,600th anniversary of the enthronement of the Emperor Jimmu, Japan's legendary first emperor. Submarine Squadron 4 was assigned directly to the Combined Fleet on 15 November 1940.

As the Japanese armed forces mobilized for an offensive against Allied forces that would begin the Pacific campaign of World War II, I-53, I-54, and I-55 departed Kure, Japan, on 20 November 1941 bound for Samah on China's Hainan Island, which they reached on 26 November 1941. All three submarines departed Samah on 1 December 1941 to take up positions to support the offensive. Tasked with supporting Operation E, the Japanese invasion of British Malaya, I-55 formed a patrol line in the South China Sea east of Kuantan, British Malaya, with I-53 and I-54 on 7 December 1941.

World War II First war patrol Hostilities began in East Asia on 8 December 1941 (7 December across the International Date Line in Hawaii, where Japan began the war with its attack on Pearl Harbor), and on 9 and 10 December I-55 participated in attempts to intercept Force Z, a British Royal Navy task force centered around the battleship and battlecruiser , before it could threaten Japanese invasion convoys. Imperial Japanese Navy torpedo planes sank the two capital ships in the South China Sea off the Malayan Peninsula on 10 December 1941 before the submarines could engage them.

Early on the morning of 14 December 1941, the Dutch submarine detected faint propeller noises, apparently those of a Japanese submarine, and at 11:00 sighted a periscope to starboard. K XII steered to ram the Japanese submarine and had closed to of where lookouts had last seen the periscope when the periscope reappeared to port. K XII abandoned the ramming attempt and broke contact by zigzagging away. The submarine she attempted to ram probably was I-54, I-55, or I-56. I-55 concluded her patrol with her arrival at Cam Ranh Bay in Japanese-occupied French Indochina on 20 December 1941.

Second war patrol I-55 departed Cam Ranh Bay on 29 December 1941 to begin her second war patrol. She patrolled the Bangka Strait off Sumatra without incident and returned to Cam Ranh Bay on 14 January 1942.

Third war patrol I-55 departed Cam Ranh Bay for her third war patrol on 31 January 1942, assigned a patrol area at the southern entrance to Lombok Strait between Bali and Lombok as a part of the A Group. After refueling at an advance base in the Anambas Islands on 2 February 1942, she proceeded to her patrol area. I-55 often is credited with sinking the Dutch 1,937-gross register ton steamer on 4 February 1942, but Van Lansberge actually was sunk in an air attack.

After the Japanese submarine expended all of her torpedoes in an attack on an Allied convoy, I-53, I-54, and I-55 received orders on 5 February 1942 to patrol in Ro-34ʼs area. On 7 February 1942, I-55 encountered the 4,519-gross register ton Dutch passenger ship Van Cloon in the Java Sea at and engaged her with gunfire, forcing her to beach herself on the south shore of Bawean Island in a sinking condition. The United States Navy patrol vessel arrived on the scene, rescued 187 people from Van Cloon, and opened fire on I-55 when I-55 attempted to surface nearby. I-55 dived and later was attacked by an Allied PBY Catalina flying boat.

Japanese forces invaded Sumatra and Java on 8 February 1942, and at 21:02 on the evening of 13 February I-55 hit the British 4,799-gross register ton armed steamer with two torpedoes in the Java Sea. Derrymore, which was on a voyage from Singapore to Batavia, Java, with a 7,000-ton cargo of military stores including ammunition and six crated Hawker Hurricane Mark II fighters and carrying 209 Royal Australian Air Force (RAAF) personnel, sank 90 minutes later about north of Jason Rock and southwest of Noordwachter Island in the Thousand Islands at with the loss of nine RAAF personnel. The Royal Australian Navy corvette quickly rescued Derrymore′s entire crew of 36 (including four gunners) and the other 200 RAAF personnel aboard.