I-10 was an Imperial Japanese Navy Type A1 submarine that served during World War II. Designed as a submarine aircraft carrier, she was commissioned in 1941 and supported the attack on Pearl Harbor, operated in the Indian Ocean — including support for the 1942 midget submarine attack on Diego Suarez — and in the New Caledonia and New Zealand areas, and took part in the Guadalcanal campaign and Marianas campaign before she was sunk in 1944 during her seventh war patrol.
Design and description Type A1 submarines were versions of the preceding Type J3 with superior range and an improved aircraft installation, and they were fitted as squadron flagships. They displaced on the surface and submerged. The submarines were long, a beam of and a draft of . They had a diving depth of .Bagnasco, p. 188
For surface running, Type A1 submarines were powered by two diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a electric motor. They could reach on the surfaceChesneau, p. 200 and underwater. On the surface, the Type A1s had a range of at ; submerged, they had a range of at .
Type A1 submarines were armed with four internal bow torpedo tubes and carried a total of 18 torpedoes. They were also armed with a single /40 deck gun and two twin Type 96 anti-aircraft guns.Carpenter & Dorr, p. 101
Unlike on the Type J3 submarines, the aircraft hangar was integrated into the conning tower and faced forward, and the aircraft catapult was forward of the hangar, while the deck gun was aft of the conning tower. Reversing the locations of the deck gun and catapult allowed aircraft launching from a Type A1 submarine to use the forward motion of the submarine to supplement the speed imparted by the catapult.
Construction and commissioning
Built by Kawasaki at Kobe, Japan, I-10 was laid down as Submarine No. 10 on 7 June 1938. Later renamed I-10, she was launched on 20 or 29 September 1939, according to different sources, and was completed and commissioned on 31 October 1941.
Service history
Pre-World War II On the day of her commissioning, I-10 was attached to the Sasebo Naval District and assigned to Submarine Squadron 2 in the 6th Fleet. By 10 November 1941, she was serving as the squadron's flagship. That day, the 6th Fleet commander, Vice Admiral Mitsumi Shimizu, held a meeting with the commanding officers of the submarines of Submarine Squadron 3 aboard his flagship, the light cruiser , and his chief of staff briefed them on plans for Operation Z, the upcoming surprise attack on Pearl Harbor in Hawaii. The attack would begin the Pacific campaign and bring Japan and the United States into World War II. I-10 and the submarine were assigned to the 6th Fleet Reconnaissance Unit.
As Japanese military forces began to deploy for the opening Japanese offensive of the war, I-10, with an embarked Watanabe E9W1 (Allied reporting name "Slim") floatplane, departed Yokosuka, Japan, on 16 November 1941, with orders to conduct a reconnaissance of areas in the vicinity of Fiji and the Samoan Islands, including Tutuila in American Samoa. She arrived at Kwajalein Atoll in the Marshall Islands on 23 November 1941 to refuel, then proceeded to Fijian waters. Off Viti Levu in the Fiji Islands on 30 November 1941, she launched her floatplane to reconnoiter Suva Bay off Suva.Prange, Gordon W., "At Dawn We Slept: The Untold Story of Pearl Harbor", Penguin Books, New York, New York, 1981, Library of Congress card number 82-5896, , page 431. The floatplane′s crew reported sighting no enemy ships at Suva Bay, but it never returned to I-10, and after a fruitless three-day search for it and its crew under radio silence, I-10 gave up the search and reported the loss of her plane and its crew to 6th Fleet headquarters.
While I-10 was at sea, she received the message "Climb Mount Niitaka 1208" () from the Combined Fleet on 2 December 1941, indicating that war with the Allies would commence on 8 December 1941 Japan time, which was on 7 December 1941 on the other side of the International Date Line in Hawaii. On 3 December 1941, she conducted a submerged reconnaissance of the harbor at Pago Pago on Tutuila in American Samoa, sighting what she identified as a United States Navy "Astoria-class" heavy cruiser.
World War II
First war patrol
Heading toward Hawaii after leaving the waters around American Samoa, I-10 arrived in a patrol area south of Oahu on 7 December 1941, the day the Japanese attacked Pearl Harbor. On 9 December, she received a report that the submarine had sighted the U.S. Navy aircraft carrier , along with orders to leave her patrol area and join the search for Lexington. While southeast of Hawaii after dark that evening, she fired one torpedo at the Panamanian 4,430-gross register ton motor vessel , which was on a voyage from Suva to Vancouver, British Columbia, Canada, with a cargo of sugar and pineapples.Edwards, p. 4. After the torpedo missed, she surfaced and attacked Donerail with gunfire, firing twenty rounds. As Donerail′s crew abandoned ship, one shell struck her starboard lifeboat while it still hung in its davits, completely destroying it and killing everyone in it. Donerail sank two hours later at . Meanwhile, I-10′s crew opened machine gun fire on her survivors.Edwards, pp. 4, 230. Twenty-seven of Donerail′s passengers and crew died in the sinking and subsequent massacre,Edwards, p. 230. leaving only 16 alive. Of the 42 people aboard Donerail, only eight ultimately survived, reaching Tarawa in the Gilbert Islands 38 days later.
On 12 December 1941, I-10 was reassigned to the Advance Force, and that day she received orders to proceed to the United States West Coast and patrol in an area off San Diego, California. On 13 December 1941, Japanese Imperial General Headquarters ordered the submarines of the 6th Fleet to bombard the U.S. West Coast. On 14 December 1941, the 6th Fleet′s commander, Vice Admiral Mitsumi Shimizu, in turn ordered I-10 and the submarines , I-15, I-17, , , , I-25, and each to fire 30 rounds at targets on the U.S. West Coast on the evening of 25 December 1941, with the commander of Submarine Squadron 1, Rear Admiral Tsutomu Sato. aboard I-9 in overall command of the bombardment. On 22 December 1941 the commander-in-chief of the Combined Fleet, Admiral Isoroku Yamamoto, postponed the bombardment until 27 December. On 27 December 1941, Sato cancelled the bombardment because most of the submarines tasked with carrying it out were low on fuel. I-10′s time off the U.S. West Coast otherwise passed quietly. On 9 January 1942 she was reassigned directly to 6th Fleet headquarters, and on 11 January 1942 she arrived at Kwajalein.
January–April 1942
After an overnight stay at Kwajalein, I-10 departed on 12 January 1942 bound for Yokosuka, which she reached on 21 January 1942. While in Japan, she was reassigned to Submarine Squadron 8 on 10 March 1942. On 12 March, she got underway from Yokosuka to search for and attack the aircraft carriers of U.S. Navy Task Force 17, which had conducted the Lae-Salamaua Raid against Japanese forces landing on the northeast coast of New Guinea on 10 March, but she had no success, and she returned to Japan, arriving at Kure on 20 March 1942.
During I-10′s stay in Japan, the German naval staff in Berlin formally requested on 27 March 1942 that Japan begin attacks on Allied convoys in the Indian Ocean. On 8 April 1942, the Japanese formally agreed to meet this request by dispatching submarines to operate off the coast of East Africa, and that day they withdrew Submarine Division 1 of Submarine Squadron 8 from its base at Kwajalein to Japan. By 16 April 1942 they had created the "A" detachment within Submarine Squadron 8, consisting of I-10 and the submarines , , , and , as well as midget submarines and the auxiliary cruisers and , which were to operate as supply ships for the submarines. That morning, the commander of the 6th Fleet, Vice Admiral Teruhisa Komatsu, the commander of Submarine Squadron 8, their staffs, and the midget submarine crews paid a courtesy call on Admiral Yamamoto aboard his flagship, the battleship , at Hashirajima anchorage. After the visit with Yamamoto, the detachment got underway at 11:00, bound for Penang in Japanese-occupied British Malaya.
During the detachment′s voyage, 16 United States Army Air Forces B-25 Mitchell bombers launched by the aircraft carrier struck targets on Honshu in the Doolittle Raid on 18 April 1942. The detachment received orders from the 6th Fleet that day to divert from its voyage and head northeast, passing north of the Bonin Islands, to intercept the U.S. Navy task force that had launched the strike. The detachment failed to find the U.S. ships and soon resumed its voyage.
I-30 and Aikoku Maru called at Penang from 20 April to 22 April 1942 before heading into the Indian Ocean to conduct an advance reconnaissance of the "A" Detachment′s planned operating area. I-10 made an overnight stop at Singapore from 23 to 24 April, then proceeded to Penang. The Imperial Japanese Army transport Urajio Maru mistakenly opened gunfire on her during her voyage, but she avoided damage and arrived at Penang safely on 25 April 1942. On 27 April, the rest of the "A" Detachment arrived at Penang, where the seaplane carrier — which had undergone modifications allowing her to carry Type A midget submarines — rendezvoused with it. I-16, I-18, and I-20 each embarked a midget submarine at Penang on 30 April 1942.
Indian Ocean operation
I-10 and the other "A" detachment units got underway from Penang on 30 April 1942, headed westward into the Indian Ocean with I-10 serving as the detachment′s flagship. The submarines refueled at sea from Aikoku Maru and Hōkoku Maru on 5, 10, and 15 May 1942.
I-10′s Yokosuka E14Y1 (Allied reporting name "Glen") floatplane began reconnaissance flights over ports in South Africa by reconnoitering Durban on 20 May 1942, where its crew found no targets of importance. Although challenged from the ground during the flight, the aircraft escaped after its radioman bought time by transmitting a false recognition signal in response. The plane made flights over East London, Port Elizabeth, and Simon's Town over the next week, and by 24 May the "A" detachment submarines were encountering heavy Allied shipping traffic as they approached East Africa. On the night of 29 May, I-10′s floatplane flew over Diego-Suarez, Madagascar, sighting the British battleship among the ships anchored there. The "A" detachment commander selected Diego-Suarez as the target for a midget submarine attack, scheduled for 30 May 1942.
On 30 May 1942, I-18′s midget submarine could not launch because of engine failure, but I-16 and I-20 both launched their midget submarines to attack the Allied warships at Diego Suarez.Rigge, Simon (1980). War in the Outposts. Chicago, Time-Life Books, pp. 107–108, I-20′s midget submarine, M-20b, managed to enter the harbor and was attacked with depth charges, but fired two torpedoes. One torpedo seriously damaged Ramillies, while the second sank the 6,993-ton oil tanker British Loyalty. Ramillies required repairs in South Africa and England. Neither midget submarine returned, and on 31 May 1942, I-10′s floatplane made a flight over Diego Suarez in the hope of locating any of the midget submarine crewmen who might have reached shore, without success. I-16′s midget submarine disappeared at sea and the body of one of its crewman was found washed ashore on Madagascar on 31 May. The crew of M-20b beached their craft at Nosy Antalikely and moved inland towards a pre-arranged pick-up point near Cape Amber, but were both killed in a firefight with British Royal Marines on 2 June 1942; one Marine was killed in the action as well.