Japanese Submarines in WWII

Japanese Submarines in World War Two – Hirohito’s Silent Hunters. By Terry C Treadwell. Pen and Sword books, Yorkshire, England 2025. 

Reviewed by John Mortimer 

The author served in the Royal Air Force and has written several books on the linkage between naval aviation and submarines: “Strike from Beneath the Sea: A History of Aircraft Carrying Submarines”, “Submarines with Wings”, and “The First Naval Air War – A Pictorial History 1914-1919”.

The Imperial Japanese Navy took an early interest in submarine development. In 1904 the Japanese Government ordered five Holland VI submarines to a Japanese modified design to be built by Electric Boat Company of Massachusetts and reassembled in Japan at Yokosuka. Two further submarines, numbers 6 and No7 were acquired, but the former was lost during a training exercise in the Seto Inland Sea with all hands. Later five submarines were acquired from Vickers, Great Britain and others from France and Italy. The Japanese continued to build submarines mainly using the British Vickers “L” class ocean going design up until the end of the First World War.

Japanese warships operated widely across the western Pacific in World War One, including in Australian waters. The Japanese navy also provided a flotilla of destroyers for operations against Austrian and German submarines in the Mediterranean and Adriatic seas.  With the cessation of hostilities Japan was granted seven ex German U-boats and negotiated the release of a further seven boats from Britain. This together with access to German technical support led to broadening Japanese views on submarine design.

During the 1920s Japanese submarine design and construction advanced rapidly and witnessed the development of large ocean-going submarines. The first such design was the I-51 class. This submarine was 91.4 metres long, displaced 1,500 tons surfaced and 2,430 tons submerged, and had a surface speed of 20 knots and submerged speed of 10 knots. It carried 24 21- inch torpedoes, had 8 torpedo tubes, together with one four inch and one three- inch gun. It was subsequently fitted with a crane to launch and recover aircraft and carried two Yokosuka E6Y1 Type 91 reconnaissance aircraft. As such it was considerably in advance of other submarines of the time.

Naval arms limitation treaties negotiated during the inter-war period meant that Japanese forces had lesser allowances for warships than both the Royal and US navies. Consequently, Japan adopted a position of developing superior performance in their warships compared to the major powers. Its strategy was also based on the attrition of adversary forces before engaging in a decisive battle. As such the submarine forces’ main role was to support the operations of the Japanese Battle Fleet. This was evidenced during its attack on Pearl Harbor, and operations off the US west coast, the Aleutian Islands and in battles in the central Pacific, such as Coral Sea, Guadalcanal and Midway.

 The author is critical of the Japanese performance of its submarine force for not taking a broader approach to its utilisation, especially that it did not wage a war on US commerce and lines of logistic support across the Pacific. In December 1941 the Japanese had a force of 64 submarines, while the USN had a total of 51 submarines of the Asiatic and Pacific fleets, some of which were destroyed by the initial Japanese onslaught. Appendices 1 and 2 – Japanese Submarine Losses and Japanese Submarine Successes reveal a slightly different picture. They show Japanese submarines sank a variety of merchant vessels and warships across the Pacific and Indian oceans. For example, in July and August 1942 I-175 attacked and damaged or sank four merchant ships off the Queensland and New South Wales coasts

, while in November she sank the US carrier Liscombe Bay.

Japanese advances in the western Pacific and margins of the Indian Ocean greatly expanded the Japanese area of operations and meant that now additional forces were required for garrison duties and logistic support, rather than direct combat operations. Poor relations between the Japanese Army and Navy further complicated matters as did the relatively limited industrial capacity of the Japanese compared to the US. The latter were able to rapidly expand their forces whereas Japan did not, nor could they replace their combat loses to the same extent. US codebreaking success also meant that Japanese naval codes could be read, and submarine communications revealed the broad area of operations of their assets.

As the situation deteriorated for the Japanese the submarine force was allotted the task of resupplying remote garrisons or assisting in their evacuation. Like the Germans, the Japanese reverted to non-conventional solutions such as kamikaze, new generation midget submarines (Koryu) and human crewed torpedo (Kaiten) developments to try and retain some initiative and stall the Allied advance.

The performance of Japanese submarines is discussed in the context of the various campaigns they contributed to, as well as the operations of opposing forces. Overall, the authors approach is descriptive and is particularly strong in its coverage of technical developments and evolution of designs, which were often innovative. The major shortcomings of the Japanese submarine campaign are highlighted. These include a broad lack of tactical doctrine, lack of attention to the early development of radar, sonar and effective anti-submarine vessels to train with, and the continued use of communications which had been deciphered by the adversary.  To some extent the submarine force was a hostage to competition between the Army and Navy, the navy’s emphasis on the decisive battle and the diversion of submarines to logistically supply the occupational overreach of land forces.

Operations in Australian waters and engagements with Australian forces are covered including the attack on Sydney Harbour, the sinking of RO-33 by HMAS Arunta and the sinking of RO-110 by HMA ships Ipswich and Launceston in company with the Indian Navy Bathurst class corvette Jumna. The author’s description of the attack on Sydney Harbour has inaccuracies – namely the cruisers HMAS Canberra and USS Chicago opening fire with their main armament, and all four midget submarines being sunk in the harbour Yt The fourth midget submarine was only discovered recently off Warriewood Beach, north of Sydney).

Overall, this book provides a broad coverage of Japanese submarines from their inception through to the end of World War Two. Its focus is on design and technical development and is particularly strong on the integration of aircraft. Its other strength is the discussion of their wartime operations, their integration into overall campaigns, and the Appendices on submarines losses and successes. The text is complemented with an excellent selection of photographs, many of which are new. I strongly recommend this book to naval historians and those contemplating the needs of our future submarine capability. The current generation of Japanese submarines now offer capabilities which are progressively bridging the gap between conventional and nuclear submarines.