5: Building a Navy

Description

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.

Sources

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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Transcript

The limitations placed upon the Japanese Navy at the Washington Naval Conference caused a complete re-evaluation of the defense policy of the Navy. Kato Kanji was assigned the task of trying to work out what it should be, and what adjustments should be made based on these new limitations. The treaty required the Japanese to abandon their goal of building an 8-8 fleet, or a fleet of 16 capital ships, and they also had to cancel the construction of 6 capital ship and the plans for 8 more. The positive side effect of all of this was that Naval expenditures decreased drastically between 1921 and 1923, dropping from over 30% of the budget to 21%. Of course, Naval planners, Kanji included, only saw the new treaty arrangements as handcuffs, limitations on what Japan could do and so they sought to find way to make up for Japanese inferiority. The planning at this point was still based on the idea that there would be a decisive fleet engagement in the Pacific sometime within the first two months of the start of the war. This was based on the fact that Kanji believed that the necessity of an early decisive engagement was a lesson that all navies would learn from the First World War. An early engagement like this ruled out any fleet expansion beyond what each navy had at the moment that the conflict began, which meant that the Japanese Navy would have 60% of the capital ship tonnage of its enemies. However Japan did have geography on its side, with both possible enemies having to travel long distances to approach Japanese territorial waters. There also no limits on the number of smaller ships that the Japanese navy could build, and they hoped to use those ships to execute a concerted attritional campaign against any enemy fleet that sailed into the Pacific. The hope was that the smaller Japanese naval assets: cruisers, destroyers, and submarines could whittle away at either an American or British fleet that was approaching the Western Pacific. This caused an emphasis to be placed on ships that could fill this role, like large submarines which had operational ranges that would allow them to shadow and attack and American fleet coming out of Hawaii. The Japanese Navy would also put an emphasis on its night fighting capabilities, hoping that this would provide an advantage especially for destroyers and cruisers during any attritional engagements. Integral to all of this was the idea that the American Fleet would move across the Pacific at the start of hostilities, probably with the aim of either protecting or retaking the Philippines. If they did not make such a move the Japanese did not really have a way, at least in these early years, of proactively forcing an engagement, that ability would only come later and only after the refinement of aircraft carriers.

After the Washington Naval Conference there was always the assumption that there would be further conferences as the years went by to clarify provisions from the treaty and to make new arrangements. The most optimistic leaders believed that these future conferences would lead to further reductions. The first attempt at this would bein in Geneva in 1927 where the major members of the five Party Treaty signed in Washington would reassemble to discuss further agreements. The Japanese plan going into this conference was to push for a 70% ratio in capital ships, which represented an increase from their existing 60%. They also planned to push for a much greater than 70% ratio in smaller ships, small cruisers and destroyers, and to make this argument more persuasive they poured time and money into rapidly building cruisers and destroyers to stay far ahead of other navies. When the conference started the best that the Japanese could get was a 65% ratio in capital ships, which was more than they had, but not enough for an agreement to be reached. The good news for the Japanese was that the most important disagreement at the conference had nothing to do with Japan and was in fact a disagreement between the British and Americans about the specifics of an agreement around cruiser types and numbers. After no real agreement was reached, the same nations would meet again in London in 1930, which would have a much more important impact on events in Japan.

In the lead up to the London Conference the Japanese would become obsessed with the idea of a 70% ratio both in capital ships and large cruisers. They had always wanted 70%, and had only compromised in Washington because they were able to trade it for the non-fortification agreement, which prevented other nations from building large naval bases in the Pacific. This seemed like a good trade at the time, but in the decade that had followed there had been advancements in various technologies which made the agreement far less appealing. The two most important of these was that the range for smaller ships had increased due to advancements in machinery and aircraft were becoming a more important part of naval warfare. Because of these facts the Japanese wanted to essentially undo the trade, getting their 10% of tonnage back in exchange for removing the non-fortification clause. Another reason that the Japanese were very concerned about getting an increase in capital ship allocation was because it was clear to just about everyone that a key part of the discussions in London would be around cruiser limitations. Assuming there were limitations placed on Japan in this area at some ratio below 100% then one of the key areas in which Japan hoped to compensate for its lesser fleet of capital ships would be gone. This is exactly what would happen at the conference, with the Japanese delegation bring brought into an agreement where they would be allowed just 60% of the tonnage for large 10,000 ton treaty cruisers. This agreement was actually worse for the Japanese than just the simple math indicates, and they would experience the same problem that the British had at the earlier conference. Basically, the Japanese had already built enough ships to match their limit, which meant that they could not build any more heavy cruisers for the duration of the treaty. This was good from a money saving perspective, but it would leave them with a fleet of cruisers that were much older than those of the American and British fleets. The large building program of large cruisers in the early 1930s did not do anything to assuage these concerns at all. If the treaty was allowed to stand and a war started in the mid 130s the Japanese would be left in a position where some American heavy cruisers were a full decade newer than any that they had. The Japanese delegation was able to get a concession in the form of lighter cruisers, with a 70% ratio, but this type of ship was already under question by the Japanese navy leadership due to concerns that smaller cruisers were simply too small for what the navy wanted to do with cruisers in the vast expanses of the Pacific. The fact that the Japanese did not get what they wanted out of the London negotiations, and that they were still stuck at 60% in capital ships, meant that while they still accepted the agreement it essentially poisoned the possibility of any further agreements. There was just kind of a general acceptance after 1930 that the Japanese would never get what they wanted out of these international arms agreements, which led many to question why they should participate. The agreement would also heighten tension between the Japanese Naval leaders on the General Staff and the political leaders in the Naval Ministry. Or as one officer would put it “In the Navy Ministry they derided the Naval General Staff as crazy, and in the Naval General Staff they denounced the Navy Ministry as traitorous.” the level of discontent became so bad that the Japanese Prime Minister was assassinated on November 14th by a Japanese Nationalist, at least partially due to the treaty which the assassin felt was a national humiliation.

Along with the frustration among naval leaders at the disappointing results of the previous naval discussions there were also events happening in the world during the 1930s which made further naval agreements more and more unlikely. The continuing expansion of Japanese involvement in China, with the invasion of Manchuria in 1931, then fighting in northern China, made the Japanese navy more bold in its rejection of international agreements and more sensitive to the idea that war was more likely. In 1933 the Japanese government would also officially withdraw from the League of Nations, an important example of the shift in Japanese attitude away from international agreements. There was also greater support among the Japanese people for an increased naval building program, partially amplified by a concerted effort by the Navy in the form of a propaganda campaign. This built up public pressure on the government to refuse to accept any unequal treaty arrangements which involved any kind of accepted smaller limitation for the Japanese navy. Instead of a 70% ratio the Navy now began to strongly advocate that anything sort of strict parity was simply unacceptable. During 1934 Admiral Mineo Osumi, the minister of the navy would be able to remove many of those who had previously supported the treaty system. These more moderate members of the Japanese Navy and Naval Ministry had been important voices when getting official acceptance of the earlier treaties, and now they were gone. Along with a demand for parity the Japanese would also decide to withdraw from the previous non-fortification agreement. They had come to believe that it held almost no value due to how much money the Americans had spent on naval bases at Hawaii, which made the Japanese believe that it was unlikely that they would put a similar effort into a large base in the Western Pacific. There were also the previously mentioned technical advancements which made the non-fortification agreement less impactful. The Japanese also planned to try and keep the arms limitation side of any discussions completely separate from discussions of events in East Asia, they did not want their actions in China from being in any way tied into possible naval agreements.

When it came time to actually meet and discuss these topics, which would occur in London in 1934, the hardline stance of the Japanese navy around the demand for parity was firmly established, but it also made negotiations with the other nations essentially a non-starter. Parity was totally unacceptable to the British and Americans, they were simple never going to sign a treaty with another nation that allowed that nation to build up to their tonnage limits. Their position was based on the theory that they both had to maintain a two ocean navy, which meant they had far greater needs for ships. Both believed that a Japanese fleet at parity with their own would give the Japanese almost free reign in the Western Pacific. Along with this parity demand the Japanese delegation, led by Admiral Yamamoto, would propose lowering the overall tonnage limits of all navies, and a drastic reduction in capital ships. However, these were mostly positions based on public relations, and the Japanese fully understood that their demand for parity meant that they had zero chance of actually happening. For months the delegations from the three nations would meet and discuss, but the Japanese refused to discuss any other matters, like size or armament limitations, without first gaining an agreement on total tonnage limits. The Americans and British were unwilling to agree on quantitative limits and so the negotiations never really got started. Eventually in December 1934 the Japanese government announced that it would withdraw from the Washington Naval treaty when it expired in 1936, this was the proper way to officially announce that it planned to not renew the treaties beyond 1936. As soon as the countdown on the treaty began plans for a building program that expanded the Japanese navy and ships that were far beyond the treaty limits was put in place which would eventually result in the most well known Japanese ships of the war, the Yamato and Musashi.

During the 1930s Japanese Naval Construction, but during and after the treaty period were structured based on four Circle Plans, or the Naval Armaments Supplement Programs, which would be approved in 1931, 1934, 1937 and 1939. These plans would be responsible for much of the fleet with which the Japanese Navy would enter the Second World War and they represented a compromise between what the Navy wanted and what the Japanese government felt they could afford. The Circle One program was approved in 1931 and it called for the creation of 39 ships, with cruisers being the main focus. However, the Japanese had agreed to not build anymore 10,000 ton 8 inch treaty cruisers and so instead they focused on creating a small class of cruisers which would mount a remarkable 15 six inch guns mounted in 5 triple turrets. This class, the Mogami class, was discussed in the Treaty Cruiser episode because while technically not a treaty cruiser, they were heavy enough to be one. They had an announced weight of just 8,500 tons, but by the time that they were actually operational they would be up over 11,000 tons, larger than most treaty cruisers. They allowed them to be more heavily armored, and have more anti aircraft protection than most other cruisers. The Mogamis would be one of the classes of ships that the Japanese would have issues actually getting to the point where they were properly stable at sea due to how top heavy they were, but they would eventually sort that problem out. Along with this new class of cruiser and then also the auxiliary ships, the Circle One program involved time and money being spent on improving Japanese naval aviation. This included carrier aircraft, flying boats, and land based attack plans that were specifically designed to assist the Navy. Over time these land based naval aircraft would become a critical part of Japanese naval strategy. During all of the circle plans naval aviation was always seen as an essential part of making up for any other numerical problems that the Japanese navy would experience both during and after the treaty period.

The Circle 2 program would be approved in 1934 and would be the last which took place within the confines of the treaty system. It would include, among smaller ships, two large cruisers and two new fleet carriers. The cruisers would be the Tone class which we discussed during the Treaty Cruisers episode, and they were designed to fill the role of scouts to the battle fleet with an emphasis on scout planes, of which they would carry 5. The two carriers would be the Soryu and the Hiryu, both of which would be part of the fleet at the start of the war. Another important part of the Circle 2 program was the continuing efforts to modernize as much of the Japanese fleet as possible. Modernizations were a very important part of the treaty period for all of the world’s major navies. Naval warfare was evolving, everybody agreed, and with it naval technology was also changing, which meant that there were always ways to modernize older ships, especially with so many ships being around from before the Washington Treaty. Most of these modernization efforts took advantage of newer technologies, like new propulsion technologies of better boilers and higher steam pressures. There were also other new technologies like better fire control and range finding. There were also modernization efforts as a way of providing more protection against new threats. As engagement ranges continued to increase guns had to be provided with a higher maximum elevation, this increased the threat from plunging shells, or shells that impacted from high angles. This required more armor on the areas of the ship that had previously been thought relatively save from shells. Then of course there were aircraft that were becoming more robust and which could carry larger bombs which required greater deck armor and also better torpedo protection to protect against the larger and more explosive torpedoes under development. All of these kinds of improvements, when completed, provided the navy with more capital ships at a much lower cost than building a new ship from scratch.

The Circle three program would be the first to take place after the treaty expired. It would contain two Yamato class battleships, two carriers of what would become the Shokaku class, and 64 other ships. Construction would begin on these ships in 1937. Almost all of these ships would be completed before the war started, and all of them would play critical roles either in the fighting directly or at least as a threat to the American fleet which would alter American decision making. Circle 4 would be approved in September 1939, and Circle 5 in 1941, both of these programs were very large including more Yamato class battleships, more carriers, and a hugely expanded naval aviation. However, very little of these two programs would actually be completed, or even really started. Circle four would just be getting started when the war began, and resources had to be shifted, and then Circle Five was just straight up cancelled after Midway because all possible Japanese resources had to be pushed into trying to make up for the shortfall in carriers and aviation assets. Those were the building plans of the Japanese Navy at a high level, next episode we will discuss some more technical aspects of what the Japanese were building, with special focus on submarines and destroyers.