ON THE MORNING of 27 April 1943, the Imperial Japanese Navy cruiser submarine I-29, codenamed Matsu, was sailing slowly through choppy waters up the Mozambique Channel, between Madagascar and the east coast of the African continent. The behemoth submarine was as long as a football field and could carry a small seaplane and a crew of 94.
The submarine was “ostensibly on a routine mission hunting enemy ships”. It was captained by the flotilla commander himself, Captain Teraoka—an odd choice for the apparently mundane assignment. I-29 was also carrying two tons of gold bars in 143 crates as well as the blueprints of the Akagi aircraft carrier and a Type A midget submarine. Its cargo also included a motley collection of other items: an experimental pressure gun, “half a ton of mail and documents, and various Japanese inventions”.

Curiously, a smaller German submarine, U-180, captained by Commander Werner Musenberg, was also sailing alongside the I-29 that day, both of them thousands of miles away from their home bases. There was strict radio silence between the two vessels as they were in enemy waters. As the sun began to set along the East African coast, the Japanese submarine crew noticed two men swimming towards them from the U-boat.[1] The duo, a German officer and a signals man, were quickly hauled on board by the Japanese sailors. They informed Captain Teraoka that their U-180 was running low on fuel and that “the exchange must take place” soon.
Provided with an inflatable boat, the Germans then made their way back to their vessel while dragging along a strong rope. Waiting on the deck of the U-boat were two bedraggled Indian men wearing life jackets. According to Commander Musenberg, “the two of them climbed, more pushed than voluntarily, into the large Japanese inflatable boat that was rocking wildly up and down”. “Clinging to the rope and inching their way across cresting waves,” they finally reached the other submarine and climbed onboard. Captain Teraoka gave an enthusiastic welcome to his special guests, the leader of the Indian independence movement, Subhas Chandra Bose, and his adjutant, Abid Hassan Saffrani.
The I-29 had left its base in Penang days earlier exactly on this clandestine mission to rendezvous with the U-180.