Never knew about this! Came across it after seeing reference to Sea Hurricanes operating from RN carrier involved in the Operation.
http://en.wikipedia.org/wiki/Battle_of_Madagascar Operation Ironclad
Allied commanders decided to launch an amphibious assault on Madagascar. The plan was known as Operation Ironclad and Allied forces, centred initially on the British Army and the Royal Navy were commanded by Major-General Robert Sturges of the Royal Marines. The Allied naval contingent consisted of over 50 vessels, drawn from Force H, the British Home Fleet and the British Eastern Fleet, commanded by Rear Admiral Edward Neville Syfret. The fleet included HMS Illustrious, her sister ship HMS Indomitable and the ageing battleship HMS Ramillies to cover the landings.
The landings
Following many reconnaissance missions by the South African Air Force, the British 5th Infantry Division's 17th Infantry Brigade Group and 13th Infantry Brigade, as well as the British 29th Infantry Brigade, and 5 Commando, Royal Marines were carried ashore by landing craft to Courrier Bay and Ambararata Bay, just west of the major port of Diego Suarez (later known as Antsiranana), at the northern tip of Madagascar. A diversionary attack was staged to the east. Air cover was provided mainly by Fairey Albacores, Grumman Martlets and Fairey Swordfish from the Fleet Air Arm, which attacked Vichy shipping. A small number of SAAF planes assisted.
September 19, 1942. Allied troops disembarking from LCA-164 in Tamatave harbour. (Photographer: Lt D.C. Oulds.)The Vichy forces, led by Governor General Armand Léon Annet, included about 8,000 troops, of whom about 6,000 were Madagascan. A large proportion of the others were Senegalese. Between 1,500 and 3,000 Vichy troops were concentrated around Diego Suarez. However, naval and air defences were relatively light and/or obsolete: eight coastal batteries, two armed merchant cruisers, two sloops, five submarines, 17 Morane-Saulnier 406 fighters and 10 Potez 63 bombers.
Following fierce fighting, Diego Suarez was surrendered on 7 May, although substantial Vichy forces withdrew to the south.
The Japanese submarines I-10, I-16 and I-20 arrived on May 29. I-10's reconnaissance plane spotted the Ramillies at anchor in Diego Suarez harbour but, the plane was seen and Ramillies changed her berth. I-20 and I-16 launched two midget submarines, one of which managed to enter the harbour and fired 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 and Plymouth.
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 its crew was washed ashore a day later.