5: Building a Navy


Hello everyone and welcome to History of the Second World War Members episode number 5. This series will be a deeper dive into the Japanese Navy during and after the Washington Naval Treaty. We will discuss the Japanese views on the treaty system and the changes to it during the 1920s and 30s and then we will look at why the Japanese decided to leave the treaty system in 1936. To end this episode we will look at the basic administrative structure of how Japan would build up its fleet through the use of what are colloquially known as the Circle Plans. In later episodes we will discuss some of the technological advancements made by the Japanese Navy and then also how they believed a war in the Pacific would develop. All of these decisions during the interwar years would leave the Japanese Navy with a fleet that would be a very capable fighting force when the war started with 10 battleships, 10 carriers, and a host of smaller ships which the Japanese would put to incredibly good use during the first year of the war. Along the way to that conclusion though the Japanese Navy would be heavily influenced by three ideas and concepts that are important to keep in mind during these episodes. The first is that there was a strong belief among the Japanese naval leadership that the decisive moment in a future war would come in the form of a decisive fleet engagement in the Jutland style where big ships with big guns would finally come to blows. The Japanese fleet, its logistical structures, and its strategic theories were built around the build up to just such a decisive engagement. The second is that the Washington Treaty had left the Japanese Navy at a numerical disadvantage when compared with the Americans and the Royal navy in terms of capital ships, which forced the Japanese into trying to find an advantage in another area. The third, and something that we will not really dive into in a large way until episode 3, is that there were a set of strategic imperatives for Japan which would override all other aspects of planning and preparation, the most important being access to natural resources like oil. These imperatives would limit the strategic freedom of action of the Japanese navy both before and during the war. One other unrelated point, when discussing the events of the Japanese Navy during this period the amount of archival information is much more limited than what you might find for the American or British navies. This means that there is some ambiguity about events and decisions which I might reference along the way.


  • From Maham to Pearl Harbor: The Imperial Japanese Navy and the United States by Sadao Asada
  • The Imperial Japanese Navy In the Pacific War by Mark E. Stille
  • Kaigun: Strategy, Tactics, and Technology of the Imperial Japanese Navy, 1887-1941 by David C. Evans and Mark R. Peattie
  • Sunburst: The Rise of Japanese Naval Air Power, 1909-1941 by Mark R. Peattie
  • The World’s Aircraft Carriers 1914-1945 by Roger Chesneau

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