In addition, the Japanese built a number of smaller submarines - "midget subs" that could be carried into place in the expected line of advance of the enemy to add, at lesser cost, to the number of units that might engage the capital ships driving across the sea to battle. These mini-subs could be piggy-backed on larger submarines, carried by cargo ships or by specially configured seaplane tenders. As set out here at p.33:
By the mid-1930s, the Japanese very secretly started to experiment with midget submarines.As it turned out, in the three best known uses of these midget subs, they were carried to the operating area by other, larger submarines. The first and, perhaps best known, use of these boats in operations against the American Navy at Pearl Harbor in December 1941. It seems that five midget subs were released from their mother submarines and were expected to either enter Pearl Harbor or wait off the mouth of the channel and pick off ships that tried to exit during the air attack. In addition they were supposed to be in place to evaluate the attack. None of the midget submarines performed well. One was taken down by the U.S. destroyer Ward (a story doubted at the time, but since well confirmed). Another, HA-19, which gained some fame in a bond-raising tour of the United States, suffered from a gyro failure and grounded:
With hulls shaped like a torpedo, no conning tower, and two muzzle-loaded torpedo tubes forward, the experimental Type A midget submarines had an original submerged speed of 24 knots...their successor prototypes were fitted with a conning tower; thus their submerged speed was reduced to 19 knots.
Japanese naval planners became convinced after extensive tests and exercises in the late 1930s that the midget[s]... could be used effectively against the U.S. battle line as part of the decisive battle strategy. "Included in these exercises," .... "were several 'push off' experiments from the [seplane tender] Chitose, which proved the feasibility of their thei utilization in long range operations." In this manner the midget submarines were to reach the vicinity of the battle. According to plans, once launched throgh hinged doors at the stern of the seaplane tenders Chitose and Chiyoda (converted in 1941 to transport twelve boats each), the prewar midget submarines were to swarm about and destroy enemy capital ships. The Mizuho and Nisshin were similar midget submarine carriers.
Ha-19, a 46-ton Type "A" midget submarine, was built at Kure, Japan, in 1938. In November-December 1941, she was transported aboard the larger submarine I-24 to the waters off Pearl Harbor, where she was one of five midget submarines launched to participate on the 7 December Japanese raid.One of those who gawked at HA-19 was President Franklin Roosevelt. To date, four of the Pearl Harbor midgets have been found, the fifth is still missing.
A non-functioning gyrocompass prevented Ha-19 from entering Pearl Harbor. After many adventures, she went aground at Waimanalo, on the east coast of Oahu. The submarine and her pilot, Ensign Kazuo Sakamaki, were captured on 8 December. Ensign Sakamaki was the first Japanese prisoner of war taken by the United States during the Pacific War.
Ha-19 was salvaged and later sent to the United States' mainland, where she was featured at War Bond drives throughout the country. After the end of World War II she was exhibited for many years at Key West, Florida. In 1991, Ha-19 was moved to Fredericksburg, Texas, where she remains on display at the Admiral Nimitz museum.
A second well-known attack by Japanese midget submarines was in the great Australian harbor of Sydney. As set out here:
The Japanese mother submarines I-22, I-24 and I-27 left Truk Lagoon on 18 May 1942 and headed south between Rabaul and Solomon Islands. Each had a 46 ton midget submarine clamped to its afterdeck. Aubrey Brown told me that the three mother submarines had been detected by No. 23 Radar Station RAAF at Fort Lytton, in Brisbane as they traveled down the east coast. This provided some warning that an attack would most probably occur somewhere along the coast.As noted in the link, the final midget sub was located in 2006 by some sport divers. More on HMAS Kuttabul here:
At 3.45 am on 30 May 1942, a Japanese floatplane, piloted by 27 year old Flying Warrant Officer Susumu Ito, was launched from submarine I-21. By 4:20 a.m. the floatplane, burning navigation lights, circled twice over Sydney Harbour near where the USS Chicago was anchored. It was initially thought to be an American plane but eventually some fighters were sent up to intercept the plane. Another plane was also reported at Newcastle. Neither could be found.
At sunset on Sunday 31 May 1942, there were five Japanese submarines positioned off the New South Wales coast near Sydney. Japanese mother submarines I-22, I-24, and I-27 launched midget submarines about 12 kms east of Sydney. I-21 and I-29 were the other two submarines supporting the attack on Sydney Harbour.
Submarine I-21 later took part in an attack of a different kind when it shelled Newcastle on 8 June 1942. On the same night Submarine 1-24 also shelled the eastern suburbs of Sydney.
At 8 p.m. midget submarine No. A14 was detected by an electronic indicator loop but was ignored due to other small boat traffic. The submarine became caught in the western sector of the anti-submarine net. The Japanese crew detonated a demolition charge killing themselves.
At 9:48 p.m. another inward crossing was reported but again ignored. It was midget submarine A from I-24 (M24). At 10:27 all vessels in the harbour were alerted of the submarines presence. USS Chicago spotted the submarine and fired on it with tracers from its pom pom guns. At the same time midget No. A21 was entering the harbour. The auxiliary naval patrol boat Lauriana, a peace-time motor cruiser and another patrol vessel, the Yandra tried to ram the midget and attacked it with depth charges.
At 11:10 p.m. HMAS Geelong fired at midget submarine A (M24), just before it fired 2 torpedoes at USS Chicago. One exploded under an old ferry, HMAS Kuttabul, killing 19 sailors and wounding 10. The other torpedo ran up on to the shore and failed to explode.
At 3:00 a.m., USS Chicago spotted midget No. A21 which had been battered by depth charges as it entered the harbour. Several craft attacked it with depth charges. It was later found disabled on the harbour floor with its motor still running. The 2 crew had shot themselves. Nine areas in Sydney were damaged by shells fired from the submarines.
HMAS Kuttabul was a Royal Australian Navy (RAN) depot ship, and former Sydney harbour ferry.More on the Sydney attack here.
On the night of 31 May-1 June 1942, three Ko-hyoteki class midget submarines of the Imperial Japanese Navy entered Sydney Harbour with the intention of attacking Allied warships. Only one of the submarines, designated M-24, was able to fire her torpedoes, but both torpedoes missed their intendeded target: the heavy cruiser USS Chicago. The torpedoes continued on to Garden Island: one running aground harmlessly, the other struck the seawall, against which Kuttabul was moored, and detonated. The ferry suffered extensive damaged and sank, killing 21 of the sailors sleeping onboard.
Another attack by Japanese midget submarines took place off the coast of Africa, in a harbor on the island of Madagascar against the British Royal Navy, which had just helped take the strategic island from the Vichy French (for background on the "Battle of Madagascar" see here). The Japanese with their long-range submarines, again fitted with midget subs on their backs, began an aggressive patrol of the east African coast, from Durban, South Africa, to the north. At the end of May 1942, the Japanese struck at the port of Diego Suarez (now Antsiranana):
The Japanese submarines I-10, I-16 and I-20 arrived on three weeks later on May 29. I-10's reconnaissance plane spotted HMS Ramillies at anchor in Diego Suarez harbor but the plane was spotted and Ramillies changed her berth. I-20 and I-16 launched two midget submarines, one of which managed to enter the harbor and fired two torpedoes while under depth charge attack from two corvettes. One torpedo seriously damaged Ramillies, while the second sank the oil tanker British Loyalty (later refloated). Ramillies was later repaired in Durban and Plymouth.An eye-witness report:
The crew of one of the submarines, Lieutenant Saburo Akieda and Petty Officer Masami Takemoto, beached their submarine (M-20b) at Nosy Antalikely and moved inland towards their pick-up point near Cape Amber. They were informed upon when they bought food at a village and both were killed in a firefight with Royal Marines three days later. The second midget submarine was lost at sea and the body of one of its crew was found washed ashore a day later.
Yes, at that time I was an RNVR Surgeon Lieutenant in the light cruiserJapanese midget submarines operated on far-ranging basis from Madgascar to the Aleutians and were responsible for a few ship losses, including an oiler in Ulithi Atoll and a destroyer escort off the Philippines. Some discussion of their "suicide" subs here.
‘Dauntless’ and she was a cruiser built prior to the First World War and her main
armament was 4 six-inch guns. Now the initial assault on Madagascar was taken
some months previously to capture the great harbour of Diego Suarez, a beautiful
natural harbour, the biggest in the world, bigger than the great harbour at Sydney.
And after the assault and the surrender of the French, the remainder of the island
remained in Vichy hands and it was decided that the rest of the island should be taken.
McB Now you mentioned to begin with that you had been present in Diego Suarez,
the main harbour in the north, can you tell us why the capture of that harbour was so
important to the British?
S Oh yes indeed. The Japanese were advancing rapidly, travelling westwards at
frightening speed, and the Fleet had fallen back, we’d fallen back all the way to India and then back to Mombasa, on the East African coast, when it was decided at high level... Sir Winston Churchill realised that here was this great harbour in this offshore island, and if the Japanese could get there they could move their entire fleet there, and then they could get up to the north of Africa, join up with Rommel and really that would have been the end of the campaign and the end of the war.
McB No I think that sort of detail is fairly well covered in some of the other
histories. But what is not covered to my knowledge and satisfaction is the part played
in all this by the Japanese submarine crews
S Yes, I can tell you that, because one night in May, when during a dinner aboard ‘Ramillies’ and this was told me by James Powell, who later came to us as captain of Marines. They were dining when they felt a thud, no more, and they didn’t know what it was and they went on deck and then there was another explosion and our oil tanker slowly sank to the bottom. We found out later on that a two-man submarine, a Japanese submarine, had been launched from one of their great I-class submarines which were operating in the Mozambique Channel, and they’d come in. We had no boom then at the entrance, but we put one up rapidly afterwards. And they’d come in, quite brave fellows, and they’d fired two torpedoes, one of which hit ‘Ramillies’ and one of which sank the tanker. But of course in a two-man submarine you don’t carry the full size torpedo and no damage was done to ‘Ramillies’. They almost made their escape but they ran aground on some rocks towards the entrance to the harbour and they were, later on, captured on the island by Royal Marines and suitably dealt with
But the real test of the Japanese midget subs could have come if it had been necessary to invade the Japanese main islands. One of the primary missions for several iterations of midget subs was for defense of the homeland. To this end, numerous new midgets were being built. Many of these were found in shipyards after the Japanese surrender:
Japanese Type D ("Koryu") Midget SubmarinesImagine a series of midget sub bases around the Japanese islands, like this one:
In a drydock at Kure Naval Base, Japan, 19 October 1945.
There are at least four different types of midget submarines in this group of about eighty-four boats, though the great majority are of the standard "Koryu" type. The two boats at right in the second row appear to have an enlarged conning tower and shortened hull superstructure. The two boats at left in that row are of the earlier Type A or Type C design, as are a few others further back in the group.
Japanese Midget Submarine Base, Okinawa Under attack by U.S. Navy carrier planes prior to the Invasion of Okinawa, circa March 1945. Two m1dget submarines and several camouflaged motor torpedo boats are in the lower left center. Other midget submarines and a small "Sea Truck" cargo vessel are visible at the edge of the bomb explosion area. Photograph was released by Commander in Chief, Pacific, on 24 March 1945.Lots of brave men rode the midget subs and a lot of brave men fought them.
Click on the pictures to enlarge them.
UPDATE: An interesting site here. And here.