Throughout the interwar period a major topic of conversation in the United States Navy was what should be done if there was a war with Japan. The results of those conversations was War Plan Orange.
Hello everyone and welcome to History of the Second World War Members Episode 20 - The United States Navy Part 2 - War Plan Orange. For most of the interwar period the United States Navy would spend a lot of time considering what it would do if it found itself at war with Japan, an enemy that for planning purposes was given the code name “Orange”. The resulting War Plan Orange would go through a series of both large and small revisions before it was officially retired in 1940 when the organization of American war planning shifted to the Rainbow plan structure. During its existence War Plan Orange, and its contents and evolution, represented an important snapshot of the beliefs of the United States Navy and Army, and what they viewed as the best course of action in the case of a war with Japan. Many details of the plan would change over time, as force structures, technology, and just how naval leaders viewed the task in front of them. It would be a topic that involved a constant push and pull between various naval strategies, with the emphasis placed on a specific belief ebbing and flowing based on the exact set of individuals leading the Navy and Army at any given moment. During this episode we will discuss much of the evolution of the plan from its inception in the years before the First World War all the way until the end of the 1930s. Then next episode we will look at how the American plans for a Japanese War would evolve during the 1930s as the naval landscape began to drastically change due to Japan’s War with China, the resumption of capital ship construction in the late 1930s, and the changing technological landscape.
While the details of the plan would be constantly in flux, the core of the plan would remain the same. it was built around the simple idea that a war would begin between the United States and Japan, with the war being based around a conflict without either side receiving appreciable help from its allies. This restriction was placed on the plan due to the fact that for the first few decades that it was in place Japan and Great Britain had an alliance, which meant that in a war with Japan the Royal Navy could become involved, which made planning for a massive naval campaign very difficult. The exact reason for the war to begin was generally assumed to be due to the Japanese expanding their control over the Western Pacific. To do this they would need to geographically expand their sphere of influence and prevent the United States from preventing that expansion. Regardless of why the Japanese attacked, it would assumed that they would do so without a large amount of warning. The American planners believed that Japan would attempt to accomplish its goals and achieve victory as quickly as possible, before the greater economic resources of the United States could be brought to bear. The planned length for the war would be in years, with the general estimate before the first world war being for the campaign to last a little less than a year. Then the First World War happened, and due to those events the length of the campaign was reconsidered and pushed out to about 2 years, still hopelessly optimistic. When it was then re-evaluated during the 1930s the timeframe for the war with Japan was finally pushed out to a much longer, and more realistic, four to five years.
The outline of the plan consisted of a conflict that would go through several different phases. Phase 1 always involved the Japanese attacking the various American bases strung across the Pacific, primarily their possessions in the Philippines. These attacks would be launched, it was theorized, by the Japanese in order to reduce the ability of the Americans to react to Japanese moves in Southeast asia to secure critical supplies that the Japanese had to import from other nations. The fact that several American held territories would fall to Japanese attack, or would at the very least be quickly besieged, was taken as a given during Phase 1, due to the simple distance involved. There was basically nothing that could be done to prevent Phase 1 from being a string of Japanese victories. All that American forces that were in the area could do was fight a delaying action, and in all probability a sacrificial delaying action. The further west a particular territory was the greater the chance that it would fall. The areas of greatest risk would expand over the years, with the primary target being the Philipppines in the years before the First World War given its relatively close proximity to Japan. The geographic positioning of the Philippines would be the factor around which so much of American planning would revolve, and which would cause innumerable problems all rooted in two key factors: distance and time. Whenever hostilities would occur the American military forces would be thousands of miles away, and it would take no small amount of time for them to move acrosss the Pacific. There were the possiblities of improving the defenses of the Philippines, but that ran into many budgetary problems that we will discuss in a later episode. Because of these problems Phase 2 was critical, with the goal of rolling back what would be the Japanese successes of Phase 1. Phase 2 would see American naval, air, and army assets move westward, almost certainly against Japanese resistance. This resistance would for most of the move across the Pacific be in the form of expendable assets designed to delay American movements and to cause attrition. Near the end of Phase 2 or in Phase 3 the Japanese and American fleets would probably come into direct confrontation, and at that point there would be the decisive surface clash that both sides believed they would win. If the American Fleet was victorious they would then proceed cloer to the Japanese home islands, which was the core part of Phase 3, and from that closer position they would push to victory. This victory would be achieved through a close blockade of Japan, with the topic of an invasion generally being only briefly touched on. Within the details of the plans for the three phases there were many differences between what the Americans believed the Japanese would do, what the Japanese believd the Americans would do, and what both sides actually planned to do, but at a basic level both of the sides were relatively correct in how they planned for the actions of the other nation. The Japanese did plan for a quick decisive expansion, and then an attritional campaign of dely, then a massive fleet battle that would decide the war. One of the interesting features of War Plan Orange, and the Japanese plans for the same scenario, is how closely they map with events of the Second World War. The interwar period is rife with military plans that were made and would prove to be absolutely incorrect, but in the Pacific the topics being discussed in the 1920s and 1930s would prove to match the events after 1941 in many ways. Even in some of the details, like American concerns that the Japanese would try to launch a quick strike against Hawaii as part of their opening moves of the war. The earliest versions even warned of a possible Japanese invasion of the islands, which would be incredibly problematic for the American Navy as it tried to move out into the Pacific. The similarities between the plans and later events would only increase after the First World War when Japan gained many very well known island chains from Germany as part of the Mandate system established at the Paris Peace Conference.
While the basic outline of the campaign was generally agreed upon, there was major disagreement about how quickly the Americans should begin Phase 2, and how quickly it should be completed. The desired speed of Phase 2 then spooled out into many other decisions like the route that the American fleet would take, how concerned it would be with establishing bases along the way, and what it planned to do after reaching the Philippines. Those who were pushing for a cautious approach, and those that were pushing for a dash to Manila would both have their own talking points to argue that their views were correct. Those that wanted a quick thrust to Manila, and then to victory, would cite concerns about the willingness of the American people to be involved in a lengthy war. Meanwhile, those who advocated for caution would claim that those same American people would support a lengthy war, as long as that length allowed for the cost in human lives to be kept at a minimu. The cautionary approach was far more concerned with losing a major fleet engagement and that being the cause for the loss of the war, while the speedy approach wanted to make that fleet engagement happen as quickly as possible to prevent the war from being lost before it happened. The disagreements between the cautionaries and the dashers would be the key point of dissension among multiple generations of military planners, and which side was in the ascendant position depended on the year that you look at. However, during the early years of planning the dashers would find themselves in control, and therefore the plans involved around getting the Fleet to the Philippines as quickly as possible.
The core problem faced by any military planner that advocated for a quick and decisive move to the Philippines was the problem of distance and supplies. It is almost 12,000 kilometers from the West Coast of United States to Manila, a massive distance when coal fired battleships only had an absolute maximum range of less than 12,000 kilometers, and that range was under perfect conditions. The most typical operational range of those battleships was only around 3,000 kilometers from their base. The switch of most ships to oil after the New York class battleships which were completed in 1911, but the coal fired battleships would stay in the fleet until they were either retired by the Washington Naval Treaty or switched over to oil in the 1920s. There were of course many islands that could be stopped at along the way, with Hawaii being the largest, but there were also many other islands that could theoretically provide sheltered anchorages for resupply. the problem was that before the First World War many of these were not controlled by either the United States or Japan, and so the ability of American ships to stop at them during a time of war was not guaranteed. There was also the problem that without the ability to pre-position supplies any supplies that the fleet did need would have to be transported in the fleet itself. Sheer distance was the challenge in that case, and during the First World War the Navy used the calculation that for every one thousand miles that the fleet sales from its base of operation, it would lose 10 percent of its combat capability, obviously this was a very abstract way of looking at it, but the concept of a fleet losing some of its effectiveness on long sea voyages was accurate. This meant a massive investment in logistical resources were required just to make the journey ,and then when the Fleet arrived in the Western Pacific it had to have a place to stay. The northern parts of the Philippines were felt to be too vulnerable to Japanese attack, and so the thought was that there would need to be a base somwhere on the southern end of the islands, but such a base simply did not exist when War Plan Orange was formulated. And this triggered the Great Western Base saga. The concept of a large naval ase in the Philippines was basically essential to any American war effort that involved a quick move to the Western Pacific, because of this it gained a lot of support among naval leaders, fulfilling a similar role to the one planned for the Singapore base that was to be built for use by the Royal Navy. The problem was that such bases cost a lot of money, at a time when military budgets were drastically reduced after the end of the First World War. This meant that no real progress was ever made on any base for the American navy. Other, and cheaper, alternatives were discussed, particularly around a large amount of work being put into the island of Guam to act as a naval base and resupply area, but then this was put on hold by the Washington Navy Treaty. As part of that treaty the Americans and Japanese agreed not to further fortify their Pacific island holdings, this pushed naval planning back toward a large logistical effort aimed at supporting the fleet without the benefit of a large base. However, the problems that this introduced was something that did not seem to be solveable during the early 1920s, even though there were investments made in very large heavy colliers and other ships designed to serve other ships while at sea.
The logistical problems along with simply a changing of naval leadership caused American planning to become a bit more cautious in the early 1920s. This meant a shift in what the American navy would do in Phase 2, while making that move across the Pacific. One of the reasons that this shift took place was due to the fact that after the First World War some of the German islands across the Pacific were given to Japan in the form of Mandates, which made taking over those islands possible during a war, which opened them up to be used as military bases. This provided the American Navy the ability to slowly push through the central Pacific through islands that would be very familiar to anybody who knows about the course of the pacific War after 1941, places like the Marshall Islands were suddenly cast as positions that would be taken form Japan and used as a staging point for further moves across the Pacific. By planning for a hop to the Marshalls from Hawaii, many logistical challenges were lessened because it was just over 2,000 miles, which meant that every ship could easily travel that distance. This also provided the fleet with greater flexibility when meeting any Japanese response because their endurance would not be a fact. From the Marshalls the next planned push was to the island of Truk. Truk was seen as thekey, because it provided so many benefits to the fleet, with the lagoon and surrounding attols providing ample berthing space. This is exactly what the Japanese would probably defend it with strong ground and naval forces, and because of this there were detailed plans on how the assult on Truk should be made, from where large battleships could find protected anchorages around atolls to what should be built on Truk after it was captured. Truk was also the last island that had a definitive set of plans drawn up for it during the early 1920s, with any planning after Truk depending on the state of the Fleet after it was taken, and how long it took before Japanese resistance was extinguished. One of the mistakes made during this period was that the planners took the absolute most pessimistic view of how the move across the Pacific could be made, and that meant stopping at every major island chain to remove Japanese resistance. This really slowed down the overall speed of the advance. It also contains some incorrect assumptions about how the Japanese would use their ships, believing that they would not send any capital ships to defend the outlying defensive islands.
One of the reasons that the cautious plan would then move out of favor once again was closely related to the change in views of the American military. The core change was that the Army believed that it could hold the Philippines for a decent period of time, and the overall worth of the Philippines was increased, which made it more important that the islands be held against Japanese aggression and then that the Navy arrived as quickly as possible. This caused the cautious island hopping approach of the previous years to once again be abandoned, with the goal shifting to getting to Manila as quickly as possible. Up to this point I have been speaking in pretty broad terms about the plans that were being created, so lets dive into some actual timeframes that would develop in the mid 1920s with this very fast approach. During this period the American Fleet was based on the West Coast, so we have to start the journey into the Pacific with the move from the West Coast to Hawaii, which would be completed in 10 days. Supplies and infrastructure would be built up in Hawaii to resupply and service any ships that required it when they arrived. The concentration of ships would number more than 550 by the time that they were ready to leave, which would happen early on the 14th day of hostilities. These departure dates were all based upon the calculation that the Philippines would be able to defend itself from any Japanese aggression for 60 days, with that time frame in mind the path after Hawaii was pretty clear. The fleet could not head too far south, because that lengthened the journey, but they could not take a route too far north because that would bring them too close to Japan. This led to the choice of a course roughly along the 23 degree north latitude. One of the real advancements that made this path and the desired pace possible were the innovations around refueling at sea. Oil made such refueling much easier, with no coal that had to be man-handled between ships, but it certainly did not solve all of the problems. During the 1920s improvements were made to the process of transferring fuel oil from one ship to another, which would be practiced and refined in the years that followed. This made the course across the Pacific possible, but no matter where that path led, there were always going to be some problems when it came to the latter parts of the journey. There was just no getting around the fact that the Japanese would have bases at places like Iwo Jima and the Bonin island chain, and these could all be home to enemy ships, submarines, and aircraft. The American fleet did have some intrinsic air power, with both the USS Langley aircraft carrier and catapult launch aircraft, but there is a real sense that they were just waving off the threat from Japanese aircraft, at least in the early 1920s. The presence of an enemy fleeet was considered, butin the end the plan was based on the assumption that the Japanese fleet would not choose to face the Americans in open battle during their spring to the Philippnes, and that they would hold off on such an attack until later. This assumption was in reality required to make the plan feasible, and if the American fleet did meet the Japanese on the dash to Manila, there probably would have been serious consequences.
After this very ambitious draft of the plan, the next several years would be spent trying to square the goals and spped of the plan with the reality of what could actually be done. The initial timelines for when the fleet would move to Hawaii and then would take the next jump was inreased until it was doubled, to a full 30 days before it would leave the islands. There was laso the problem of the analysis of how many men would be required to actually hold the islands of the Philippines, because of cause the Navy was not going to be able to defend the islands with just ships. This would instead be transporting army forces that would relieve the forces that were already in the Philippines. Those forces would have to be built up over time to launch further phases of the campaign, a process that many in the Army beleived would take up to two years. This meant that the fleet would then have to be supplied for those two years, and they had to be able to not just exist but to stage combat operations during that time. With no large dry dock in the Philippines, decisions had to be made about how to ensure such a lengthy stay was possible. In the earlier plans where the movement across the Pacific was done much more slowly the problems of supporting the fleet were lessened because the goal was to create bases along the way so that things could leapfrog across the Pacific. In the dash to Manila there was no time for those bases to be created. An additional challenge was added due to the fact that after the initial fleet was pushed accross, more ships would be arriving in the Philippines at almost monthly intervals, and with each additional ship supply and maintenance became a greater concern. These were problems that would never be adequately solved, even though a good amount of effort was put into logicial planning including more reserach into refueling at sea and design work done on portable dry dock facilities, both of which would be of value after 1941. Another area that saw a lot of evolution during the mid and late 1920s was around how air power was considered as part of the plan. And it would be air power that would eventually cause yet another move to a more cautious approach. This was because even as early as 1925 it was obvious that air power was going to be an important factor to consider when planning any naval campaign, and in their quick move to Manila the American Fleet would be forced to leave a bunch of Japanese island bases behind, many of which might be able to host Japanese aircraft. The ability of the fleet to project air power to deal with these threat was limited, and in the mid 1920s it was clear that land based aircraft would have clear superiority. Not only did it make the initial advance more difficult, but it made it very challenging to justify leaving Japanese bases scattered throughout the Pacific without any attempt to neutralize them. Air power would also be a problem when trying to land troops on the Philippines themselves, because it was likely that the Japanese would have some amount of presence on the islands themselves, and the landing of American troops might even face resistance. This required additional planning and discussion, especially in the case of the fleet being at the end of a very long sea voyage. By the late 1920s all of these problems, and another shift in naval leadership meant that the plans once again became more cautious. A new round of fresh Orange plans would be made starting in 1926, the dash to Manila was still present in these plans, but it was greatly tempered, and that tempering would continue over the next decade.
It would be during this period that the first real detailed plans for what Phase 3 would be were devised. Phase 3 as it was developed revolved around a series of operations that would bring about the end of the war, primarily through economic means. To do this the overall control of the American fleet would be have to be pushed closer to Japan, to blockade the Japanese home islands, and action that would inevitably trigger a response. The exact point that the Japanese would launch their full fleet into an engagement was ont hat the Americans were not quite sure about. The Orange Plan that was developed in the late 1920s was based on the premise that the Japanese would wait as long as possible before sending out their battlefleet, choosing to use smaller attacks to reduce American forces in the meantime. It was believed that this would change as the American fleet approached the Ryukyu islands. These islands stretched from the souther tip of Japan and went down towards what was known at the time as Formosa, with the most famous island in the chain being very familiar due to later events, Okinawa. These islands would be encountered by the American fleet as they moved north from the Philippines. The Americnas were confident that the fleet battle that would occur somewhere in the Ryuku’s and they would achieve victory. With this victory and the massive reduction in Japanese naval power that would be its result, the American Navy could then move into a position to closely blockade Japan. It was believed that this would have to be maintained for at least a year before the Japanese would begin to consider surrender due to lack of food and other materials. Critically, and I think interestingly, during the 1920s there was never any real serious possibility of invading the islands of Japan, the challenges involved in such an operation were massive due to many reasons, including the sheer number of men that would be required. I realize that this is an episode about the navy, but to pull from the plans from the United States army and their thoughts on the possibility of success for an invasion “extremely doubtful . . . regardless of our greater potentiality in man power and munitions, because the enemy can always concentrate forces greatly superior to the successive Expeditions into which our land forces must be organized for overseas transportation.” Next episode we will track the course of War Plan Orange as it was forced to deal with shifts in Naval strength, both in the air and as the navies of the world began to rearm.