“Diego-Suarez Raid” propaganda postcard, Madagascar, May 1942.

“Diego-Suarez Raid” propaganda postcard, Madagascar, May 1942. The U.K. Royal Navy battleship HMS Ramillies was torpedoed and damaged by an I.J.N. midget submarine launched from the mothership, I-20, 10 nautical miles off the coast. The same midget sub is also credited with sinking a 7000-ton oil tanker in the harbor, too, while under depth charge attack.

“On 27th April 1942: ‘A’ detachment’s submarines I-16, I-18 and I-20 arrive at Penang and are joined by tender NISSHIN that had earlier been converted to carry midget submarines. On the 30th three Japanese ‘mother’ submarines are loaded with a Type A Kō-hyōteki-class midget submarines, a type which were also used in the 1941 attack on Pearl Harbor and the 1942 attack on Sydney Harbour.

“After refitting, the three submarines arrived three weeks later on 29 May on station off of Madagascar. I-10‘s reconnaissance plane spotted HMS Ramillies at anchor in Diego-Suarez harbour, but the plane was spotted and HMS Ramillies changed her berth as the floatplane returned to I-10. Upon the floatplane’s return, Captain Ishizaki orders a midget submarine attack for 0230 on 31 May.

“I-20 and I-16 each launched two midget submarines; only one managed to enter the harbour.

“The two-man crew piloted the craft to a point where they could get a good line on HMS Ramillies. The first torpedo ran true and impacted just forward of A turret, ripping a 20-30 foot hole in the side of the ship. Although taking on a list and having to flood their magazines the battleship remained afloat, saved by its anti-torpedo bulges.

“However the sudden loss of weight caused by the firing one of the torpedoes meant that midget submarine was suddenly buoyant and bobbed to the surface. A lookout on the nearby 6,993-ton oil tanker British Loyalty spotted the conning tower of the submarine. Someone on the tanker managed to get an anti-aircraft gun pointed in the direction of the midget submarine and squeezed off a burst. The volley flew wide and the submarine submerged before the gun could be re-aimed.

“The British escorts in the harbour then started steaming about dropping depth charges and trying to find the Japanese midget. But the shallow waters frustrated the ASDIC system. Remarkably the submarine stayed in the harbour, and manoeuvred around for a killing shot on HMS Ramillies. A second torpedo was lined up and fired, running true.

“However just before impact, the Loyalty steamed in-between the torpedo and the battleship, making an nunfortunately-timed break for open water, putting the tanker in the wrong place at the wrong time for her — but inadvertently saving HMS Ramillies.

“The crew of one of the midget submarines, Lieutenant Saburo Akieda and Petty Officer Masami Takemoto, beached their craft (M-20b) at Nosy Antalikely and moved inland towards their pick-up point near Cape Amber.”

– Japanese Midget Submarine Crews Hunted in Madagascar, Royal Marines (U.K.) History