There were midget submarine attacks allover the PTO in the opening months of WWII including an attack into Sydney harbour in June 1942
Australia Attacked - Sydney Harbour
"The bodies of the four Japanese crewmen from the midget submarines launched by I-22 and I-27 were recovered when these two midget submarines were raised. They were cremated at Sydney's Eastern Suburbs Crematorium with full naval honours. Rear Admiral Muirhead-Gould, in charge of Sydney Harbour defences, along with the Swiss Consul-General and members of the press, attended the service. The admiral's decision to accord the enemy a military funeral was criticised by many Australians but he defended his decision to honour the submariners' bravery. He also hoped that showing respect for the dead men might help to improve the conditions of the many Australians in Japanese prisoner of war camps.
and 11 June 1942]After the recovery of the two midget submarines a composite was constructed using the bow section of one and the stern of the other. It was decided to use this composite midget submarine to raise money for the Royal Australian Navy Relief Fund and the King George Fund for Merchant Sailors. The composite submarine was first put on display at Bennelong Point, now the site of the Sydney Opera House, and people paid a small fee to see it. It was then transported by truck on a 4000-kilometre journey through south-eastern Australia raising further funds. Eleven months after the submarine raid, the composite submarine was installed at the Australian War Memorial in Canberra.
In 1968, Lieutenant Matsuo's mother travelled to Australia to visit the spot where her son had died. During her visit she scattered cherry blossoms in the water where her son's midget submarine had been located and later she presented a number of gifts to the Australian War Memorial.
In November 2006, part of the mystery of the midget submarine from I-24 was solved when divers discovered the wreck of the submarine off Sydney's northern beaches. We will probably never know if Lieutenant Ban and his navigator, Petty Officer Ashibe Mamoru intended to rejoin their 'mother' submarine or whether they had no intention of returning and simply scuttled their vessel".
There was also a midget sub attack in madagascar 31 may 1942, in which the Bribattleship Ramillies was extensively damaged
Imperial Submarines
30 May 1942:
About 10 miles E of Diego Suarez. At 1740 (local), I-16 launches Ensign Iwase Katsusuke and PO2C Takada Kozo's midget submarine M-16b to penetrate the harbor.
At 1710, about 9 nautical miles E of Diego Suarez, I-20 launches Lt Akieda Saburo and PO1C Takemoto Masami's midget submarine M-20b. At 2025, Lt Akieda fires one of his two 17.7-inch torpedoes at RAMILLIES. The torpedo holes the bulge and bottom plating opening a 30-foot by 30-foot hole in the port bulge forward of "A" turret. The battleship's electrical system suffers damage and power is lost all over the ship. The six-inch armor belt above the site of the explosion is displaced and the forward magazines and shell rooms (15-inch main caliber and 4-inch AA) flood. At 2120, while corvettes drop depth charges nearby, Akeida fires his other torpedo and sinks 6,993-ton BRITISH LOYALTY in about 65 feet of water.
31 May 1942:
Akieda and Takemoto depart the bay and head NNW. After the midget's battery is depleted, M-20b is beached at Nosy Antalikely (Antali Keli) islet. Lt Akieda attempts to scuttle his craft, but the charge fails to explode. Both sailors reach shore and contact natives, who arrange transport to the mainland. Akieda and Takemoto head for the recovery area near Cape Amber where I-20 is to wait for two days.
Iwase, Takada and midget submarine M-16b go MIA. The wreck of M-16b is never found.
1 June 1942:
I-18, still carrying her midget submarine M-18b, finally arrives at the recovery area and joins the search.
Around 1100, Lt Akieda and PO1C Takemoto visit Anijabe village to buy some food. While most villagers are friendly, one contacts the British hoping to get a bounty for his information.
2 June 1942:
Amponkarana Bay (12-00S, 49-12E). In the morning. Lt Akieda and PO1C Takemoto are intercepted by Royal Marines' Commando No. 5 after the Japanese had made 48 miles on foot. During an ensuing gunfight both Japanese sailors and one Marine are killed. A watch and a pack of cigarettes with IJN markings are found, as well as a report addressed to the CO of I-20.
That same day. the body of an unidentified IJN sailor, presumably M-16b's Iwase or Takada, is found on a beach off Diego Suarez.
Destroyer HMS DECOY arrives with Constructor Captain H. S. Pengelly, RCNC, Fleet Constructor Officer, Eastern Fleet, aboard. Pengelly inspects HMS RAMILLIES and confirms she is fit for sea. however it will be many months before she is again operational.
3 June 1942:
After the other mother submarines depart the recovery area, I-20 surfaces and unsuccessfully tries to contact the midget submarines by firing flares and sending radio signals. At 1800, I-20 leaves the recovery area.
Temporary repairs of HMS RAMILLIES are completed and she departs for Durban.
9 June 1942:
Mozambique Channel. The day after sinking Norwegian steamer WILFORD, LtCdr Otani Kiyonori, skipper of I-18 orders midget submarine M-18b jettisoned.
1972:
A makeshift monument is erected at the place where Akieda and Takemoto perished.
10 November 1976:
The Japanese Embassy erects a plaque at the same place with a text in both French and Japanese that says: "Here died two brave Japanese sailors on 3 June 1942".
3 July 2001:
Japan. The Japanese Maritime Self-Defense Force (JMSDF ) erects a monument to the four midget crews. Present are the crew of JMSDF training vessel KASHIMA and the ceremony is led by Rear Admiral Yasui Nobuharu.
Lt ( j.g.) Kanda of HA-13 and his two crewmen were each promoted one rank, posthumously.
Lt ( j.g.) Ota went on to become navigating officer of the ill-fated I-52 and perished with her in the Atlantic Ocean in 1944.
Initially, the British thought another Vichy submarine made the attack and, therefore, did not alert the rest of the fleet. As a result, Sydney, Australia received no warning. After emergency repairs, RAMILLIES made for Durban, Union of South Africa where she was docked for temporary repairs from June to August 1942. Later, RAMILLIES returned to Plymouth, England where full repairs were completed from September 1942 to June 1943. In June 1944, RAMILLIES participated in the D-Day invasion.
BRITISH LOYALTY was later refloated and towed to Addu Atoll where, on 9 Mar '44, she was torpedoed and damaged by German submarine U-183. On 15 Jan '46, BRITISH LOYALTY was scuttled and sank off Addu Atoll.
The limited remains of Akieda and Takemoto's midget submarine "M-20b" were found about two weeks after the attack sitting upright on a reef within an area of volatile surf. According to historian/author Kimata Jiro, a recent NHK documentary showed the aft section (now completely submerged) in the same location. The propellers were salvaged and are on display at the midget submariners' grave site