2: Imperial Japanese Navy - Origins


The Imperial Japanese Navy would explode onto the world stage with its victory at the Battle of Tsushima in 1905. In the decades that followed it would become a key player in naval discussions around the world.


  • Naval Policy Between Wars. Volume I: The Period of Anglo-American Antagonism 1919-1929 by Stephen Roskill and Corelli Barnett
  • Warships After Washington: The Development of the Five Major Fleets 1922-1930 by John Jordan
  • The British Battleship 1906-1946 by Norman Friedman
  • From Mahan to Pearl Harbor: The Imperial Japanese Navy and the United States by Sadao Asada
  • Kaigun: Strategy, Tactics, and Technology of the Imperial Japanese Navy, 1887-1941 by David C. Evans and Mark R. Peattie

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Hello everyone and welcome to History of the Second World War Members Episode 2 - An Asian Navy. While the Royal Navy had been the strongest navy in the world for generations there were new challenges that it would have to face after the First World War. One of these was the growing strength of the Japanese Navy. The Japanese Navy would explode onto the world stage with the battle of Tsushima, defeating the Russian Baltic Fleet and proving that they were a match for Western navies. In the postwar years the Japanese Navy sought to ensure that their navy was a match for an aggression from any other nation. The primary threat would quickly transition to the growing strength of the United States Navy, but of course the actions of the Royal Navy could not be ignored. In this episode we will discuss the history of the Japanese Navy up to the First World War, and then discuss the Navy’s plans for after the conflict was over up until the start of the Washington Naval Conference.

The modern Japanese navy traced its roots back to the 1860s. It was at that point that education and training of officers and men grew in importance as technology became increasingly important at sea. A Naval academy was established in 1869 to further this process and to ensure that the Japanese Navy could match any in the world in terms of training. From these early beginnings some of the features of the later Japanese Navy were already present, including the extreme rivalry between the navy and the army and also internal friction between competing interests within the service itself. During this time the relationship between the Navy and the government was already put in place, with the service being controlled mostly by the Naval General Staff instead of by the civilian Naval Ministry. This gave the navy a good amount of autonomy, but also meant that the government would have many issues controlling the military, and later this arrangement would prove to be a liability. One of the first major successes of the Japanese Navy would come during the first Sino-Japanese War in 1894. It would be during that conflict that the Navy would put in place the modern tactics and theories that it had been trying to learn and implement over the previous two decades. Many of these concepts were borrowed from western Navies, which went along with purchasing ships from abroad but even at this point the Navy was morphing those foreign theories into something uniquely Japanese, a threat that would continue over the next several decades. In 1902 the Anglo-Japanese Alliance would be signed, which did not commit either nation to entering a war with the other if they were only attacked by 1 other nation, but it did commit them to action if they were attacked by 2 other nations. This agreement was important to both Japan and the British Empire, for the British it lessened their need for basing ships in the Pacific, at a time when the threat from Germany in home waters was beginning to increase. For the Japanese it gave them the national prestige of an alliance, and specifically a naval alliance, with the British Empire. It also provided the Japanese with the security to move forward with their plans for a future war with Russia without having to worry about the Royal Navy becoming involved against them.

During the Russo-Japanese War the Japanese Navy would experience many successes, and those successes would cast their shadow over all of the actions of the Army and Navy until the Second World War. It was monumental for the Japanese armed forces not just to win a victory in the war, but a victory over a Western European power. The focal point, at least for the Navy was the Battle of Tsushima, an absolutely crushing victory by the Japanese Navy over the Russian Baltic Fleet which had sailed halfway around the world only to be destroyed. In naval terms, this was the Japanese Trafalgar, and the success would be studied by Japanese Navy officers and Naval officers around the world as they all looked at Tsushima to try and learn what it meant for the new era of naval combat. Of the many changes that would be written about extensively in the following years one of the most important was that during the Russo-Japanese War the navies had engaged in fire at ranges that were previously unheard of. This very long range firing would continue during the First World War, and the ranges would only continue to grow during the interwar years. Beyond this tactical change, along with others, there were also philosophical concepts that were seemingly proven at Tsushima what would alter naval thinking in Japan and elsewhere, in Kaigun: Strategy, Tactics, and Technology of the Imperial Japanese Navy, 1887-1941 David C. Evans and Mark R. Peattie explain some of these “The impact of the Russo-Japanese War on world naval thinking has less historical significance than the legacies it provided to the evolution of Japanese naval doctrine. Four key ideas helped shape this doctrine: the concept of the decisive fleet engagement determined by big guns; the validity of a strategy of attrition against a numerically superior enemy; the preference for quality over quantity in naval weaponry; and the importance of nighttime torpedo tactics.” These impacts would be incredibly important to how the Japanese Navy looked at and made decisions about naval warfare in the following decades. It would be used as the basis for some decisions and the justification for others. The idea that naval combat had been, and in the future always would be determined by big ships with big guns was present in all of the major navies during this period, and Tsushima had been exactly what they believed a large fleet engagement would look like. The Japanese also believed that a key role in their victory had been the distances that the Russian forces had to travel before the fleets met, and the usage of naval attrition to make that journey even more uncomfortable was a concept that the Japanese would put particular focus on. In the case of both the United States and Royal Navy’s the enemy names would have to cross thousands of miles before the reached the Japanese territory, and this gave the Japanese plenty of time to prepare and also opportunities to put in place attritional actions. The possibility of being numerically outnumbered, much like at the beginning of the Russo-Japanese war, pushed the Japanese Navy to continue to put emphasis on training and design, hoping to always have the best constructed and trained fleet in the world. These types of conclusions were not necessarily harmful in any real way, other than maybe the priority given to battleships, but that was a mistake that all of the world’s navies would make, Maybe the most detrimental lesson that the Japanese naval leaders would take from the battle was the concept that a massive, all or nothing, final climactic battle at sea was the most important feature of Naval warfare. The idea that this type of battle was destined to happen, and that it would decide the war was central to Japanese naval theory. This type of assumption, and its belief that one massive defeat could end a war, was a mistake that the armies and navies would make in the years before the First World War. That war would prove that nations were fare more resilient to failure, and this was a lesson that the Japanese did not take into account. There were also some circumstances around the Russo-Japanese war that make it a poor conflict to try and glean information from. The most glaring reason was that the Russian military, and the Russian Navy, made some incredibly poor decisions, absolutely monumental mistakes. The consequences of some of these mistakes were not fully appreciated by the Japanese leaders, who attributed their victories to their good decisions instead of the poor decisions by the Russians. This would lead to future warplanning in which enemies were expected to make some of the same mistakes, the most important being an overextension into Japanese territory.

The United States would become far more involved in events in the Western Pacific after they acquired the Philippines from Spain after the Spanish-American War. However, this event did not instantly turn the country into the focus of Japanese naval planning. It would not be until the 1907 Japanese National Defense Policy, in the wake of the defeats of Russia, that the United States would be named as a hypothetical enemy for the Navy. During this time the planning for these operations were done on an annual basis, with the naval staff updating their plans against hypothetical enemies on a yearly basis. Many of the operations with which the Japanese would begin the Second World war were either initiated or continually refined during this period. This included the invasion of the Philippines, the occupation of Guam, the neutralization of Hong Kong, and the invasion of Malaya. These operations were planned and updated year after year for decades before the start of the war in 1941. A similar type of planning was occurring in the United States at this time, where “War Plan Orange” would be the primary outline for a war with Japan. Unfortunately, while we have very detailed information about the evolution of War Plan Orange, information we will work through in a future episode, a similar level of detail is not available for Japanese plans during this period, the basics of the plan are known to us though. Even that this very early period the basics of the plan for the next 30 years would be present, the most important aspect of the plan was to use the geographic distance between the United States and the Philippines against the United States Navy and wait for them to overextend into the Western Pacific before initiating the final massive fleet battle.

One of the important Japanese naval theorists during this period was Sato Tetsutaro. Sato saw the United States as the primary enemy to future Japanese expansion, and because of this he believed that the Navy was far more important than the Army to the future of Japan. In his appraisal of a future war he believed that the Japanese faced some serious problems. Looking at the situation before the First World War, Sato believed that the United States would continue to increase the size of its battlefleet, eventually he would put his estimates at the United States having 60 capital ships in 1920s, which was much higher than they would be in reality but such a massive enemy fleet was part of Sato’s plans and was used to justify his suggestions. The pessimistic view caused Sato to advocate for a very cautious approach to the United States, at least in the near term future. The goal during this period was to maintain friendly relations with the United States while preparing for future Japanese naval expansion. Important to this expansion was Sato’s belief that Japan could challenge the United States in the future, even if he also recognized that the United States had much larger economic and industrial potential. He believed that the United States had two important weaknesses when it came to war with Japan. The first was that the United States would always be forced to divide its navy between the Atlantic and Pacific oceans. The second was simply the distance that the United States fleet would have to travel if it wanted to bring the war to Asia. It would first of all take time for the distance to be traversed, but it would also be a huge logistical challenge during the years of coal burning ships. These problems for the Americans led Sato to set the assumptions of how strong the Japanese fleet needed to be in relation to the United States fleet if Japan wanted to win a war. He began with the assumption that the aggressor, which in this case would be the American Fleet moving across the Pacific, would need to have an advantage over the Japanese of about 50% if it wanted to guarantee victory. If this was the case, and with the United States still having defense commitments in the Atlantic, Sato believed that Japanese strength of 70% of the American Navy was enough to guarantee Japanese victory. For those who have listened to the serious of episodes on the Naval Arms Race from before the First World War, this was very similar to the logic that Tirpitz used when deciding on how strong the German fleet needed to be to threaten the Royal Navy. In both cases, Sato and Tirpitz, they were depending on the global commitments of their enemies to sap their strength, and then also expected the enemy to come charging into their territory. Sato would also advocate for two concepts that would become critical to Japanese Naval through, the first was a push to make sure that the Japanese ships were always qualitatively superior, and the idea that the Japanese could use attritional tactics against a westward moving American fleet to whittle away at its assumed advantage.

This attrition would become a key pillar of Japanese naval strategy during the interwar years as aircraft technology improved, and it would gain a boost after the First World War when Japan was granted many islands in the Pacific which had formerly been German colonies. These two changes were critical because they solved two major issues that the Japanese had when trying to force attrition on an American fleet. Before the First World War the endurance of smaller ships at sea was very limited, destroyers, submarines, and even small cruisers were limited in endurance and it was a laborious and slow process to resupply coal at sea. However, the increase in range of aircraft, and the increased adoption of oil burning in destroyers provided the Navy with a much greater range of action. The new bases in the Pacific just increased this range even further. The plan would evolve in such a way that these new islands were seen as a barrier against American aggression, key points of defense which would attack and hopefully reduce the numbers of, any American fleet. So technology and new possessions solved some of the logistical problems with the Japanese plan to wait for the enemy to advance. Key to this strategy was an almost reckless drive by the United States navy into the Western Pacific, but this type of advance had already been seen by the Japanese, when the Russians had charged into the Japanese fleet at Tsushima.

However, this brings us to one of the core dissonances in the plan. The Japanese acknowledged that they were at a disadvantage when it came to a protracted war with the United States, the economic and industrial base of Japan just could not measure up. This pushed the Navy into believing that a single powerful battle at sea could end the war. Geography and the balance of forces during and immediately after the First World War meant that the Japanese would have to be on the defensive. This would give the initiative to the Americans, and there was no way for the Japanese to force action. The only way that they could possibly do this was through the invasion and capture of the Philippines. This was part of the Japanese plan, and for a long time the United States would plan to do exactly what the Japanese were hoping, execute a quick dash across the Pacific to try and rescue their colony. However, throughout the evolutions of War Plan Orange this fleet movement lost favor due to the logistical problems that could not be solved. This caused the United States Navy to begin to move towards a more cautious approach, which was somewhat similar to what was actually going to happen after 1941. In this approach the Japanese Navy would be at a serious disadvantage. Japanese planning was focused on a single decisive blow delivered while the Japanese fleet was mostly intact, launched against the United States fleet reduced by distance and time. There was little provision for what to do if the enemy instead took a slow approach, using its much larger industrial capacity to build a fleet that could not be assailed.

Some of those problems would only make themselves known in the future. Before any of those plans could be put in action, the Japanese Navy needed ships. To try and improve the ability of Japanese shipyards to build new warships the Japanese government worked out a deal with Vickers in 1910. The plan was to build a battlecruiser, the Kongo, in British shipyards with Japanese engineers highly involved in the planning and construction. Then all of the design specifications would be provided to the Japanese who would then build three more identical ships in Japan. This would make the Kongo the last foreign built Japanese capital ship, an important milestone for the navy that had been heavily dependent on foreign construction up to that point. The Kongo class ships were part of a naval construction program that included the Fuso class battleships, and all of these ships would mount 14 inch guns, at the time 14 inch guns were the largest in the world, although they would soon be surpassed by the Queen Elizabeth class’s 15 inch guns. A key point is that all of these ships were pre-Jutland in design and construction and it would only be with Nagato class, which would begin construction in August 1917 that some of the design considerations from the First World War naval actions were taken into account. The armor and weight distribution was greatly altered on the Nagatos based on the news that reached Japan about those naval clashes in the North Sea. The Nagatos would also mount 16 inch guns, the largest in the world at the time. They would also be the first Japanese capital ships to burn oil instead of coal, but they would retain a mixed boiler setup, with 15 that were oil burning but 6 that could burn either fuel. This hybrid setup was a compromise between the proven technology of coal burning and the new and far more efficient oil. There was another class of even larger battleships initially designed in 1917, but these were put on hold for 3 years to await developments at the end of the war.

One of the reasons for the delay in the new ships was a re-evaluation of the global naval situation after 1917. Key to Japanese considerations was the continued expansion of the United States Navy, in 1916 they had ordered 10 capital ships, and then that number was increased a few years later. Such a massive expansion put the United States on the path to having the most powerful battlefleet in the world. To try and meet this challenge the Japanese Navy proposed an eight-eight-eight fleet concept, an expansion from their previous goals of just an eight-eight fleet. For a triple eight fleet the Navy would have three fleets all built around 8 capital ships, with a mix of battleships and battlecruisers. To reach this figure 3 new capital ships would be started every year, and then three would be completed each year as well, resulting in all 24 capital ships being completed in 8 years. This would have represented a massive expansion of the Japanese fleet, and a similarly massive expansion of the naval budget. This caused the Finance Ministry to make it clear that if naval budgets continued to balloon to the expected levels it might cause serious damage to the Japanese economy. Like many post-war naval plans this triple eight plan would be derailed by the announcement of the Washington Naval Conference.

The designs for some of the ships that would have made up this larger fleet were completed before the Conference. The defensive nature of Japanese plans caused them to make a few different choices when compared with their largest rivals. One example of how this altered ship design was the fact that the Japanese put larger engineering plants in their designs. This had the benefit of giving the ships greater speeds, an important tactical advantage, but this additional speed came at the cost of total fuel storage and range. This trade off was considered acceptable due to the defensive nature of Japanese naval plans. One change that would help would be a shift to oil, which provided a much greater range by volume. However, for Japan the shift to oil fired ships introduced a new set of problems that the nation found incredibly difficult to work around. For Japan sourcing oil was very problematic, it had essentially no domestic supply and so everything had to be imported. This caused the Navy to initiate a large stockpiling initiative which was seen as a national defense priority. However, no matter how much oil was stored in the home islands it could not solve the issue of complete dependence on imported oil. This issue was given greater priority because of the fact that the largest source of that imported oil was the United States, which was now seen as one of the most likely enemies in a future conflict. The problems of Japanese access to oil would drive Japanese strategic decision making throughout the interwar period,a nd it is a theme that we will be coming back to again and again for as long as this podcast lasts. However, in 1921 the Japanese naval plans got put on hold because of the Washington Naval Conference, which will be the topic for the next episode.