I-400 Japan's Secret Aircraft-Carrying Strike Submarine - Objective Panama Canal

by Henry Sakaida, Koji Takaki, Henry Kakaida

The I-400 'super submarine' was one of the most monstrous creations to emerge from the Second World War and in its time it was the largest submarine ever built. It was considered to have been one of Japan's most secret weapons - indeed the Allies remained unaware of its existence until it surrendered in late August 1945. At more than 400 ft long, weighing 5,700 tons, carrying a crew of 200 and possessing a range of over 50,000 miles, the I-400 carried three Seiran attack floatplanes in a hangar built on to its deck ahead of the massive conning tower. The Imperial Japanese Navy tasked the I-400 with a secret mission to attack American cities and to destroy the Panama Canal. This book is the result of many years of meticulous research. The authors have traced and interviewed three of the original six pilots slated to fly the Seirans on their hazardous missions. They have revealed - for the first time - the story their aircraft being painted in fake US markings for their final mission.The book contains hundreds of astonishing photographs, many previously unpublished, showing the I-400 from both outside and inside as well as its hangars and aircraft.

144 pages, Hardcover

First published May 13, 2006

Reviews

[Emmanuel Gustin · Rating 4 out of 5]

A short but detailed account, based on Japanese sources with useful additions from the recollections of and pictures taken by American sailors who were involved in the capture of the I-400 and I-401. It emphasises primarily the stories of the Japanese who served aboard these ships, large and unique “submarine aircraft carriers”.

There is a brief history of IJN (Imperial Japanese Navy) submarine operations in WWII, which despite the occasional success where mostly disappointing despite a large investment in resources. Side note, during the war the IJN built 121 new submarines to a total of about 144,000 tons, while the US Navy acquired 293 for a total 310,000 tons. If that seems a huge gap, it was actually the category in which the IJN came closest, being out-built only two-to-one, Indicative of the importance they attached to this weapon. The huge I-400 was unique, a highly specialised strike weapon which represented a considerable investment of ingenuity, resources and manpower. This book describes how the concept evolved and was implemented. Their only combat mission was cancelled just in time because of the Japanese surrender, and the crews against all odds survived the war. It is a gripping story which would make a good submarine movie.

There are some technicalities which may not be entirely correct. Mostly these seem to be due to awkward translations from Japanese to English, or poor understanding of IJN practices. (For example, I suspect that the Nanzan was designated M6A1-K because it was normal IJN practice to append a new function letter when the function of a type changed, and K indicated a trainer.) But these are details. This is not a technical account and the amount of detail on the I-400 and M6A is limited. It is a story about people, and in that it succeeds very well. It seems to be brutally honest. The book is very well illustrated and produced.