While the big ships with the big guns would get so much of the publicity during the interwar years the Japanese, more than most, put a huge emphasis on smaller classes of ships. They looked at these smaller classes of ships as a way of making up for the fact that they would always be at a disadvantage in capital ships due to the Washington agreements. In this episode we will discuss 4 different types of ships: submarines, destroyers, cruisers, and aircraft carriers. In each of these classes the Japanese would try in different ways to make up for their capital ship deficiency, and each was shaped by the idea that they were subservient to the capital ships. Their design goals were to do what they could to support the big ships in the expected massive climactic battle that would theoretically end a war in the Pacific. Some of this support would be at the tactical level, supporting other ships in the moment of battle, but others would be a more distant support, applying attrition to an enemy fleet as it tried to move out of its based and then through the vast areas of the Pacific that would have to be traversed before the two fleet would be able to meet.
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Hello everyone and welcome to History of the Second World War Members Episode 6. While the big ships with the big guns would get so much of the publicity during the interwar years the Japanese, more than most, put a huge emphasis on smaller classes of ships. They looked at these smaller classes of ships as a way of making up for the fact that they would always be at a disadvantage in capital ships due to the Washington agreements. In this episode we will discuss 4 different types of ships: submarines, destroyers, cruisers, and aircraft carriers. In each of these classes the Japanese would try in different ways to make up for their capital ship deficiency, and each was shaped by the idea that they were subservient to the capital ships. Their design goals were to do what they could to support the big ships in the expected massive climactic battle that would theoretically end a war in the Pacific. Some of this support would be at the tactical level, supporting other ships in the moment of battle, but others would be a more distant support, applying attrition to an enemy fleet as it tried to move out of its based and then through the vast areas of the Pacific that would have to be traversed before the two fleet would be able to meet.
During the First World War submarines had really come into their own as a serious naval platform. There had always been theories about how submarines could be used in a naval war, and many navies had put a lot of time and energy into the design and development of submarines before the war, but it was the the experiences that were had during the conflict that validated and invalidated some of the assumptions made about submarines and made it clear that submarines could seriously alter the course of the war at sea. However, during the interwar years there were few massive technical changes to the structure and design of submarines. There were evolutionary changes for sure, with some technological improvements in diesel engines, batteries, and usage of hydraulics just to name a few, but there were not many huge leaps. However, there were many conversations that would occur about how to use them. On the Japanese side most of these discussions revolved around how the submarines could best be utilized to support the battlefleet. To determine how the Japanese navy should utilize its submarine assets Rear Admiral Suetsugu Nobumasa was put in command of the First Submarine Division. Suetsugu was not a submariner by experience, although he of course studied German operation from the First World War like every other submarine officer during the interwar years. He was firmly of the belief that the submarine as a platform could be utilized to equalize the status of the capital ship fleets in the Pacific. During his time as the commander of the First and then also the Second Submarine Divisions the roles of the submarine would be broken up into several different focus areas: reconnaissance, port blockade, cooperation with aircraft, and the use of submarines in fleet operations. All of these were structured around the idea that the current role of submarines in the Japanese Navy, one of short range defense, should be transformed into one of long range and mostly offensive operations. One item that was not focused on was anti-commerce actions. Part of the neglect for this area of operation was logical, when compared to say the German situation the Japanese did not have as obvious of a target as the Atlantic convoys. However, those commerce targets did still exist, especially as enemy fleets would extend across the Pacific which was something they were almost certain to do. This neglect of commerce operations would have two major consequences: first and most obviously it would make it more challenging for the Japanese to focus on anti-commerce operations during the war. Second, and more importantly to the course of the war, it meant that the Japanese limited their study on the effect that a submarine based anti-commerce campaign in the Pacific could have. During the war the consequences of the American campaign against Japanese shipping would be catastrophic, and by not putting the research time into how to launch such a campaign the Japanese also failed to spend the appropriate amount of time on possible countermeasures. While the Japanese did not consider commerce raiding to be important, they certainly considered the role of enemy fleet attrition to be critical for submarine operations. The plan was to send submarines, by 1930 the plan was to be six submarines, to enemy bases when it appeared that hostilities were approaching. Then once the enemy fleet left its base the goal of the Japanese submarines was to shadow the enemy fleet, although not necessarily to attack it, and to keep it under surveillance. At some point before the two fleets met the submarine assets would then execute an attack with the goal of reducing the number of enemy ships as much as possible. This plan became just the assumption for how submarines would be used in a conflict, and because of this the Japanese would build submarined based on performing these tasks. Obviously there were features of a submarine that would be critical when trying to keep up with an enemy fleet, speed and range being the most important. This meant that the Japanese would spend time developing a cruiser submarine, which was loosely based on a German design. These subs had to have the range to make it to enemy ports and the endurance to stay there for some period of time, but then also the speed to follow the enemy fleet once it left. The Japanese designers would be able to achieve these goals for the most part, even if the early designs and prototypes that were tested throughout the 1920s and 30s had problematic diesels and batteries. The range on what would eventually become the J class submarines was very impressive, 24,000 miles, which would allow them to go to the West coast of the United States and stay there for weeks at a time. They would also have two 5.5 inch deck guns for use against merchant ships, and 6 torpedo tubes. This was an impressive technological accomplishment, the only problem was that the plan for the submarines, and really the entire plan for how the Japanese envisioned submarines would work in the Pacific theater would proved to be flawed, which would be a common theme that would affect Japanese ship designs. It would prove to be incredibly difficult to keep up with and shadow an enemy fleet while at sea, and so the Japanese submarines would be pushed into other roles.
Moving up the naval hierarchy, next up is the destroyers. Destroyers were present in all navies, and during the First World War for many they had went through a period of evolution. Before the war the destroyer had been seen primarily as a torpedo boat, which would use its speed during a fleet action to approach enemy capital ships, launch its load of torpedoes and then largely disappear. The events at Jutland with the German destroyers are a textbook example of how destroyers were designed to be used. However, this shifted over time due to the need for destroyers to be a bit more useful in other roles, nowhere was this more important than in commerce protection, which would see the destroyers take on the bulk of anti-submarine operations. The Japanese still viewed their destroyers primarily in the light of how they could assist the fleet, and this meant they still focused primarily on night time torpedo operations. Much like the submarines the goal of destroyer operations was to launch attacks before the main fleet engagement and to try and reduce the strength of the enemy fleet. It was believed that the most efficient way to achieve this goal was through night time torpedo attacks. The destroyers created for this role were very good, for example the Fubuki class which would be built between 1926 and 1931 would be some of the most powerful destroyers in the world at the time. They would carry 18 torpedoes with nine total torpedo tubes in three triple launchers. This would be pretty much the template for Japanese destroyers between the wars, and the Fubuki class would be qualitatively better than most if not all other destroyers at the time, at least when it came to straight up firepower. The Japanese worked hard to keep them a secret, and then even halted destroyer production for a period of time to try and reduce the likelihood that other navies would produce a response.
We have discussed Japanese cruisers in some detail in the Treaty Cruisers episode, but it is worth nothing some of the design considerations that the Japanese put in place for the cruisers based on the role that they were intended to play. Much like other nations the Japanese were restricted in the size of their heavy cruisers during the treaty period, although they were perhaps a bit more optimistic about their designed displacements limits and they would often go over the treaty limits by thousands, and not hundreds, of tons. The Japanese generally had a different view of the role of their cruisers when compared to the other nations, which again comes back to how they saw their role during fleet actions. For example when compared to the British, who had a far greater emphasis on cruisers as commerce protection, the Japanese put a much greater emphasis on firepower. But there were limits to how much firepower, or at least gun based firepower, could be placed on ships that were so limited in size by the treaty. To try and pack more firepower onto their ships the Japanese would put a much greater emphasis on torpedo armament for their cruisers than many other navies. At the same time that this emphasis was in place the US Navy was moving away from torpedo armament on cruisers altogether, and instead they endorsed the belief that gunfire would be far more important in cruiser combat. The Japanese would move in the opposite direction, and they believed that the torpedo would be decisive weapon in battles, even if they were just between cruisers. This difference in opinion would widen during the 1930s, with the Americans eventually just removing torpedo capabilities altogether. A great example of the Japanese dedication to the torpedo equipped cruiser was the Furutaka class which was first introduced in the mid 1920s, which at 7,000 tons would still contain 12 torpedo tubes. These ships, as designed, would be used in a very similar way to the Japanese destroyers, launching night torpedo attacks against enemy ships. The emphasis on torpedoes for destroyers and cruisers would also cause effort to be put into ensuring that the ships had the best possible torpedoes, with these efforts eventually resulting in the type 93 torpedo. This torpedo was designed to enable the Japanese torpedo equipped ships to launch their attacks at long ranges with a higher likelihood of success and it was almost indisputably the most advanced torpedo in the world at the time. While trying to push as much firepower as possible onto their ships was core to Japanese ship building philosophy, designer Hiraga Yuzuru was concerned that it was being taken too far. And when given the requirements for the next set of Japanese cruisers, and the first treaty cruisers, he raised many concerns about the compromises that were being made to the basic ship designs. The initial requirements that he was given called for 10 8 inch guns and 8 torpedo tubes that would be in fixed mounts below the aft upper deck. Hiraga believed that these tubes would be both dangerous in terms of ship survivability and also seaworthiness. However there were constraints on how much a design could change after the basic concept was approved by the navy.
Stability and reliability at sea would be a big problem for Japanese cruisers during this period and it would really come back to design and requirement issues. The ships were continuously heavier than planned, which meant that they sat lower in the water and had greater structural stresses than were accounting for by the design. Hiraga would link all of this back to the Navy’s demand for too much firepower while at the same time not being willing to compromise on speed and protection. These problems would all come to a head in the mid 1930s when, during the 1935 Annual Grand Maneuvers the Fourth Fleet would attempt to ride out a large typhoon off the coast of Japan. Many of the ships rode out the storm just fine, but the larger destroyers and the heavier cruisers took a serious beating. For example the Fubuki class destroyers would be rolling at 75 degrees, dangerously close to capsizing and some of the ships were damaged to the point of almost not making it back to port. This was all indicative of the ships simply being too heavy, and especially too top heavy, for their designs, and the storms would also reveal that their longitudinal strength was simply not sufficient. This meant that not only did they roll horrifically, but they also started to come apart. Construction on new ships of similar classes was halted, and most of the ships had to come into port for extensive redesign and reconstruction. Eventually they would be made far more seaworthy, but only be sacrificing some of their endurance, speed, and armament and of course fully ignoring previous treaty limits. The renunciation of the treaty system in the years before the war would solve many of the problems experienced by Japanese ships, because they could be as large as they needed.
Japanese aircraft carriers would become legendary in the early years of the Second World War, however Japan would exit the First World War without any real experience in naval aviation, or really military aviation in general which put them at a huge disadvantage when compared to their most likely enemies. There were efforts in Japan to remedy this problem during the war, but there was simply nothing that could bridge the gap that was developing based on the the experience that other nations were getting in the European theater. To try and kickstart this area of technology, which seemed to be growing in importance, the Japanese would reach out to their, at the time, allies the British. There were several competing viewpoints on the British side of the request. The Admiralty was not thrilled with the idea that they would essentially be providing the Japanese with detailed information about new weapons systems and then providing them with training on how to use them. To counteract this there were strong desires among the British aircraft industry, facing a massive reduction in government orders after the war, to expand their sales possibilities into Japan, which if possible would be very lucrative for the British economy. Eventually a deal would be worked out, at least partially due to the Royal Navy’s ever present gross underestimation of Japanese abilities. The eventual mission sent to Japan would be known as the Sempill mission. It would go to Japan with over 100 aircraft of 20 different models, five of which were from the Fleet Air Arm. The mission would also bring with it the technical information about aircraft, engines, early British carriers, and also experiences learned in combat. All of this information would play a large role in the creation of the first Japanese carrier, the Hosho. The procedures used on the carrier and then also the design of Japanese aircraft that were used on the carrier were also heavily influenced by the Sempill mission and then various information exchanges that followed. Japanese naval aviation was given a boost which, much like the United States, the Japanese navy was left with several incomplete capital ships after the Washington Naval Treaty which it was unable to complete. In the United States these would become the Lexington and the Saratoga, and for the Japanese the Akagi and the Kaga. With Japanese naval aviation expanding in this way, it became imperative that the Japanese really started to consider how they planned to use them in combat.
While the Japanese navy was showing great interest in naval aviation, during the 1920s, and even really until the mid 1930s this aviation was meant for a very different purpose than what would be seen after 1941. During most of the interwar period aircraft were slow, had short range, and they could only carry a very modest armament payload, at least in relation to what they would need to be able to do serious damage to a large naval vessel. Because of this carriers were meant, once again, to support the battle line. They would provide spotting to supplement the planes that all major naval vessels were beginning to carry, and more critically they would do their best to secure air superiority to allow friendly spotting aircraft to exist in the combat airspace while also trying to remove the enemy’s spotting planes. It would only be later in the 1930s when aircraft began to improve with larger engines, all metal construction, and retractable landing gear that they began to have the ability to launch and execute aerial strikes with any real hope of being able to inflict serious damage. This meant that for most of the interwar period the emphasis on naval aviation was built around the assumption that it was through aerial superiority that the range of battleships could be extended. It was believed that Japanese ships could begin to fire at up to around 34,000 meters, at this distance it was incredibly challenging to actually spot the fall of shells from aboard ship. This made spotting aircraft really important, and they would be carried aboard the battleships themselves, floatplanes which were dedicated spotting platforms. These aircraft would also be important if the enemy used a smoke screen or a smoke curtain to try and bloke visibility between ships as the distance was closed, which would forfeit any advantage that the Japanese ships had in their engagement ranges.
Overall engagement range was seen as a critical area where the Japanese could obtain a qualitative advantage over their enemies. This caused the Japanese to emphasize extreme long range gun fire and also influenced the design of their ships. One of the reasons that the Japanese ships had their very characteristic pagoda superstructures was to give the maximum possible elevation for gun spotting. There were also alterations made to gun turrets to allow for the best possible gun elevation to allow for very long range fire. This allowed Japanese 16 inch guns to have a maximum firing range of over 41,000 yards. Now, being able to shoot a shell very far and being able to hit something with that shell are obviously very different conversations. It was hoped that spotting aircraft would assist in solving this problem, and there were also more and more advanced fire control systems that were being created. The Americans would have an advantage in this area, with some breakthroughs that allowed for more automatic stabilization, critical to hitting ships while moving as well as very precise automatic aiming mechanisms on the guns. The Japanese would also work on these same problems, and would also try to develop similar capabilities but they would end up with mechanisms that were large, heavy, and required a lot of manpower to use. These systems would never be truly perfected before the war, and during the early years of the conflict long range gunnery would often result in very disappointing results for all navies, and it was certainly not just a Japanese problem. I will close out this episode by just saying that, while the Japanese made many decisions based around the idea of a large fleet confrontation that would never happen, that does not mean that they were making more mistakes than other navies. During the interwar period a huge amount of planning, design, theory, and construction would go into being prepared for situations that would never occur. Next episode we will take a wider look at how the Japanese believed a war in the Pacific, especially one against the United States, would be structured, and how they planned to win it.