Type A-class Midget Submarine
|Displacement||46 tons full|
|Machinery||Battery/electric (600hp), two counter-rotating screws|
|Range||100nm at 2 knots, 80nm at 6 knots, 18nm at 19 knots|
|Armament||2x450mm muzzle-loaded torpedoes, 1x140kg scuttling charge|
|Submerged Speed||19 knots|
Contributor: David Stubblebine
This article refers to the entire Type A-class; it is not about an individual vessel.
Ko-hyoteki Ko Gata Type-A midget submarines were 78.5 feet long, displaced 46 tons, were armed with two muzzle-loaded torpedoes, and had a crew of two. Normally, they were transported to and from their target areas on the decks of larger Type C1 submarines. About 60 Type A's were built and were the first midgets to be deployed.
Pearl Harbor – 7-Dec-1941
Five Ko-hyoteki Type A's armed with type 97 torpedoes were launched from five Type C1 mother-submarines as part of the attack on Pearl Harbor. Their orders were to attack any ships that attempted to leave the harbor.
One of these five midget submarines, I-18tou (the midget launched from mother-submarine I-18) was depth-charged in Keehi Lagoon outside Pearl Harbor between the harbor entrance and Honolulu, now under the extended runways of Honolulu International Airport (US Navy divers recovered her wreck on 13-June-1960 with both torpedoes still aboard).
I-24tou (Ha-19) lost her way due to a malfunctioning gyrocompass, ran up on reefs twice, and finally grounded herself on Waimanalo Beach on Oahu's east shore. The sub was captured with both torpedoes still in her tubes and her commanding officer became the first Japanese POW of the war.
I-20tou was spotted as it was entering the harbor and was sunk by gunfire from USS Ward (NOAA's Hawaii Undersea Research Laboratory [HURL] located her wreck offshore in August 2002 with both torpedoes still aboard).
I-22tou entered Pearl Harbor and fired both torpedoes toward USS Curtiss and USS Monaghan just after the air attack started. One torpedo ran aground on Ford Island and the other hit a pier off Pearl City. Monaghan rammed and then depth-charged the sub. (The wreck was recovered shortly after the attack and later in the war was used as fill during an expansion of the Pearl Harbor Submarine Base. The hulk was dug up in the 1960's but reburied almost immediately. According to some sources, the remains of her crew remain aboard.)
I-16tou sent a radio report during the evening of December 7th that the attacks had been successful and claimed credit for sinking USS Arizona. Photographic analysis conducted by independent researchers and published by the United States Naval Institute in 1999 suggests a Type A inside the harbor successfully fired torpedoes at USS West Virginia and USS Oklahoma during the air attack. I-16tou was never picked up by any of the mother-subs and the submarine's final resting place is not known.
Light Cruiser USS St. Louis reported she was fired upon by a midget submarine as she broke out of Pearl Harbor at about 0930-1000 but the "two torpedoes" exploded against a submerged reef before reaching the ship. Destroyers pounded the area of the sub with depth charges as St. Louis continued on her sortie.
It would seem there were not enough torpedoes for all these attacks to have come from the five midgets. Six of the ten torpedoes deployed were still in the tubes of their sunken or captured vessels and two were fired at Curtiss and Monaghan inside the harbor. The photo analysts suggest two torpedoes were fired against Battleship Row and St. Louis reported two torpedoes were fired at her. That's 12 torpedoes. All of the 22 large Japanese submarines deployed around Oahu at the time survived the trip to Hawaii and none reported firing any torpedoes that day. The photo analysis was first printed in 1999, three years before the wreck of I-20tou was discovered with both torpedoes still aboard. So at the time these conclusions were published, two torpedoes were unaccounted for. With the discovery of I-20tou in 2002, the question is reduced to which account is more credible: the attack on Battleship Row or the attack on St. Louis. The authors of the 1999 photo analysis have authoritatively repeated their conclusions in several forums recently, but under objective scrutiny they do not hold up.
Sydney Harbor – 31-May-1942
At 0300 on 30 May 1942 one of five large Japanese submarines launched a reconnaissance aircraft northeast of Sydney, Australia. After circling the harbor, the plane returned reporting "battleships and cruisers" in the harbor. In reality, the largest ship present was the heavy cruiser USS Chicago. The flotilla's commander decided to attack the harbor with midget submarines the next night. The next day the five submarines approached Sydney Heads and released three Type A midget submarines at about 0430 to begin their approach to Sydney Harbor.
The outer-harbor defenses detected the entry of the first midget submarine at about 2000 hours, but it was not identified until it became entangled in an anti-torpedo net that was suspended between George's Head and Green Point. Before HMAS Yarroma was able to open fire, the submarine's two crew members destroyed their vessel with demolition charges and killed themselves.
The second submarine entered the harbor at about 2148 and headed west towards the Harbor Bridge, causing a general alarm to be issued by the Naval Officer in Charge, Sydney. About 200 yards from Garden Island the submarine was fired on by the cruiser Chicago. The submarine then fired its two torpedoes at the cruiser. One torpedo ran ashore on Garden Island but failed to explode. The other passed under the Dutch submarine K9 and struck the harbor bed beneath the depot ship HMAS Kuttabul where it exploded, killing 21 sailors: 19 Royal Australian Navy and 2 Royal Navy. Its mission complete, the submarine then slipped out of the harbor and disappeared (her wreck was located in November 2006 about 20 miles north of the harbor; it is now protected as a war grave).
The third submarine was sighted by HMAS Yandra at the entrance to the harbor and was depth-charged. Some four hours later, having recovered, it entered the harbor but it was subsequently attacked with depth charges and sunk in Taylor Bay by vessels of the Royal Australian Navy. Both members of the submarine's crew committed suicide.
The two submarines that were recovered from inside the harbor were identical. Their remains were used to reconstruct one complete submarine that toured Australia for a year before being delivered to the Australian War Memorial in Canberra in 1943, where it still remains on display.
Diego Suarez, Madagascar – 30-May-1942
Japanese submarines I-10, I-16 and I-20 arrived off Madagascar 29 May 1942. I-10's scout plane spotted the 31,000 ton battleship HMS Ramillies at anchor in Diego Suarez harbor but the aircraft was spotted and Ramillies changed her berth. On 30-May-1942 I-20 and I-16 launched two Type A midget submarines, one of which managed to enter the harbor and fire two torpedoes while under depth charge attack from two corvettes. One torpedo seriously damaged Ramillies, while the second sank an oil tanker British Loyalty (later refloated). Ramillies was later repaired in Durban, South Africa and Plymouth, England before sailing with distinction in the Normandy Invasion.
One of the submarines was beached at Nosy Antalikely and the crew moved inland towards their pick-up point near Cape Amber. When they bought food at a village, they were informed upon and they were both were killed by Royal Marines a few days later. The second midget submarine was lost at sea and the body of one its crew washed ashore a day later.
Type A boats were also employed off Guadalcanal and the Solomon Islands in 1942-43, where they achieved modest success against U.S. shipping. They were deployed around Midway, the Aleutians, the Bismarck Islands, the Philippines, the Marianas, and Okinawa as shore-based defensive units, but their overall effectiveness was negligible at best.
Type A-class Midget Submarine Interactive Map
Type A-class Midget Submarine Operational Timeline
|30 May 1942||Before dawn, the floatplane of Japanese submarine I-10 conducted a reconnaissance mission over Diego-Suárez harbor, Madagascar, spotting British battleship HMS Ramillies, a tanker, a freighter, and an ammunition ship. At 1740 hours, I-16 and I-20 launched midget submarines M-16b and M-20b 10 miles from Diego-Suárez. M-20b fired her torpedo at 2025 hours, damaging HMS Ramillies and putting her out of action for a year. At 2120 hours, corvettes HMS Genista and HMS Thyme counterattacked with depth charges but failed to hit the Japanese midget submarines. Shortly after, M-20b fired her second torpedo, sinking British tanker British Loyalty.|
|31 May 1942||Japanese submarine I-10 launched her floatplane for a reconnaissance mission over Diego-Suárez harbor, Madagascar to evaluate damage caused by the midget submarine attack that had taken place during the previous night.|
|31 May 1942||Japanese submarines I-22, I-24, and I-27 launched three midget submarines 7 miles off of Sydney, Australia. At 2235 hours, one was caught in torpedo nets and was scuttled by her own crew of two (both were killed in the process). The two others continued into Sydney Harbor.|
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James Forrestal, Secretary of the Navy, 23 Feb 1945