3: Washington Naval Conference


In late 1921 the major naval powers of the world would gather in Washington D.C. to discuss the possibility of a naval limitation treaty. The result would be the largest, and really most successful, arms limitation treaty in human history.


  • 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

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Hello everyone and welcome to History of the Second World War Premium Episode Number 3 - The Washington Naval Treaty. After the 1916 naval expansion plan was approved by the United States Congress, the United States Navy would soon be building its navy up to a strength of 35 capital ships, this number would then increase to 50 with the 1919 naval Bill. This massive expansion of what was already the second largest navy in the world meant that the world was very quickly spiraling into another naval arms race. Before the First World War the British and German Empires had engaged in such a race, with massive amounts of money being spent on their warships. In the 1920s it was possible that 3 nations would participate in an even larger and more costly building competition with the United States, Japan, and British Empire all investigating large fleet expansion programs. However, at least in 1920 it was the United States that was in control of a possible arms race. It had the economic and industrial capacity to out build any other nation in the world, and it could choose to do so, or it could chose a different path. A different path would be chosen. After the end of the Wilson Presidency, his successor, President Harding was far less interested in participating in an arms race. Instead the new American government would begin to investigate the possibility of an international arms limitation treaty. This investigation would eventually result in the Washington Naval Treaty, which has been a topic that we have brushed up against in the previous episodes of this series. The agreement would completely change the composition and future plans of the major navies around the world. It would for the first time put restrictions not just on the number, but also the size and armament of naval vessels. There would be a specific schedule on when ships could be retired and replaced, with only certain rotating into retirement during specific years. The end result would be the most comprehensive and significant arms reduction treaty in history. However, it would be strictly related to naval strength, there would be no discussion of limitations on air or land power, due at least partially to the insistence of the French. This was a reasonable limitation on the conference, trying to introduce any non-naval restrictions would have brought the conference into a whole host of complications, complications that would doom many attempts at disarmament treaties in the 1930s.

The catalyst for the Washington Naval Conference was actually a rumor that spread throughout the major governments of the world that the British intended to call a conference in London in 1921. This conference would discuss the situation in the Pacific and in Eastern Asia with the goal of trying to assure a lasting peace between the powers within interests in the region. The American Secretary of State, Charles Evans Hughes, had already proposed the idea of a conference of the major naval powers to discuss arms limitation to President Harding, and the President would give him the go ahead to move forward with his plan. They wanted to announce their conference before the British had a chance, because it would be essentially impossible for any discussion of the political situation in the Pacific to take place without also discussing the naval side of the equation. Hughes wanted those naval discussions to occur in America, framed by American leaders, and within a conference dedicated not to larger political goals and relations but instead specifically the reduction of naval armaments. On July 8th 1921 American ambassadors in London, Paris, Rome, and Tokyo were told to propose the conference to the governments of their host countries. Then on July 11th when the United States Senate approved an amendment to the existing Naval Appropriations bill that would authorize the President to call a conference on naval limitation. The announcement of the conference by President Harding invited the governments of Britain, Japan, France, and Italy to participate with China, Holland, Portugal, and Belgium invited to take part in the discussions of arrangements in the Pacific and Eastern Asia, where their colonial possessions gave them a legitimate level of concern. All of the nations would accept the invitation, if only because the American Naval building program that was already underway represented a threat to every Navy in the world, and possibly all of them combined, and so any limitation discussions, if it then led to a reduction in American Naval spending, was a benefit to all other navies of the world.

When the Conference was announced, the reaction in London was, for many, a sigh of relief. The Royal Navy exited the First World War with the largest navy, on paper, but one made up of older ships that had been put through the ringer during the war. They needed to invest massive sums of money into maintenance and modernization efforts, which was a challenge for the cash strapped British government. The Board of the Admiralty gave Admiral Chatfield the responsibility of preparing the official British position going into the conference. He would be given the guidance by the government that the most important aim of the British position was the maximum possible reduction in expenditures on naval construction and maintenance. These reductions should be made only as long as the defense position of the empire was not compromised. The Committee of Imperial Defense had slightly more detailed thoughts on what the British position should be. Out of fear that such provisions would mire the conference in detailed discussions that would never resolve, the Committee believed that specific agreements on the size and technical composition of the navies should be avoided. Instead they believed that the British should just propose a simple limit on the number of capital ships. The Committee also wanted to see submarines abolished, for I think obvious reasons, but they had little hope that this would actually happen. There was not a clear agreement among the British government, the Committee, and the Admiralty before the British delegation left for Washington in October. However, unlike in modern times, the delegation still have several days to discuss their position as they transited the Atlantic on the ocean-liner Olympic. The eventually agreement of the delegation was that the British would suggest a simple limit on ship numbers. There were also many discussions about aircraft carriers among the British representatives. The British were the world leaders in naval aviation at this point in history, which really meant they had one aircraft carrier completed and capable of fleet operations, with three more in some stage of construction. At this very early stage Chatfield, in a memo to the rest of the delegation, hit on what would become a critical component of the future agreement, and that was the suggestion that some currently under-construction capital ships could be converted into aircraft carriers. These conversions would eventually take place, and many of those converted ships, like the Lexington and Akagi would be an important part of their respective navies well into the Second World War.

In Washington similar preparations were underway to determine the specific position that the United States would hold going into the conference. During these discussions there were a few issues that were taken into account. The first was that, at the time of the conference, the British and Japanese still had a naval alliance when dated back to well before the First World War. This created the possibility that a war between the United States and either Britain or Japan would result in a war against both. The core of the American discussions were around proportional strength allocations to the various navies. There was the understanding that the British and Americans would probably have to be equal, with the British almost certainly unwilling to be given anything lese. The general hope by the American Naval Board was that Japan would accept a fleet of 50% the size of the United States, which would be the same size allowed for the other powers of France and Italy. The Board also believed that any naval limitation would only come into play after the already existing building programs were completed, especially since many of the ships of those programs were already under construction. It would only be after all of these modern ships were created that any force restrictions would come into play, which would be met with the removal of older ships. This plan was rejected by the American political leaders, because one of the most important objectives of the conference from a political perspective was a massive reduction in naval expenditures, which could only be accomplish with a change to current plans. Instead of finishing out the existing building plans Hughes and others wanted to suggest a building ‘holiday’ on capital ships, which would be a period of 10 years in which no new capital ships would begin construction for any navy around the world. This would eventually be a key part of the American position, and for the most part the political leadership would simply ignore the guidance provided by the Naval Board. They would instead push for an immediate holiday, the cancellation of current building plans, the scrapping of some ships already under construction or nearing completion, and a reduction in existing fleet strength.

The Japanese Navy was generally more skeptical of what would occur at the conference. However, the Naval Minister at the time, Kato Tomosaburo was very supportive of Japan entering into some kind of naval agreement. Kato based this interest upon concerns that in the new form of warfare, as showcased during the First World War, which placed so much emphasis on economic and industrial power, Japan would be heavily disadvantaged when compared with the United States or the British. Because of the fact that Japan was never going to be able to outbuild the United States, and really probably could not even keep up with a determined United States building program Kato believed that it was better to enter into almost any limitation agreement than to allow an unrestricted building race to develop, a race that Japan would lose. While Kato Tomosaburo was the Naval Minister, he did not have completely control over the Navy, and there were a sizeable number of Japanese naval officers that believed that any naval arms limitation agreement with the United States or any other nation would be a catastrophic mistake for Japan. The leading advocate for this viewpoint was Vice Admiral Kato Kanji. Kanji and those who agreed with him did not reject the idea that the United States had a much larger industrial base and that they could, if they were determined to, outbuild Japan, but they did disagree on what the Japanese response should be. Kanji’s primary concern was that the larger industrial base of the United States meant that if the Japanese accepted naval limitation, and especially a limitation agreement that left the Japanese navy smaller than the United States Navy there would never be a point in the future where that difference could be reduced. And if a conflict did occur the industrial base of the United States would allow it to quickly expand its navy, leaving Japan in the dust. To counteract this very real concern the Japanese would need to create and maintain as large of a fleet as possible which would allow it to enter into a conflict as strong as it could be, fully understanding that once the conflict began it would probably be impossible for Japan to expand at the same rate as its enemies. The two Kato’s, Tomosaburo and Kanji, would attend the Washington Naval Conference, with Kato Tomosaburo as the lead delegate and Kato Kanji as his aide. However, they would never come to an agreement about the best course of action for Japan, even after the conference. The split within the Japanese navy would only resolve itself when the faction that rejected international cooperation took control and caused Japan to exit further discussions on naval limitation in the 1930s.

The Conference would begin during the second week of November 1921 and it would open with Hughes introducing the American position for the conference. The position described by Hughes was one that was simplified and it was fully understood that it would simply be a starting point for further negotiations. During this introduction many of the features of the later treaty would already be present. Hughes would suggest a 35,000 ton limit for new capital ships, which was smaller than capital ships that were under construction and even some that were already completed like the HMS Hood. He would suggest a building holiday on all new capital ships for a period of 10 years, and then once that holiday was over only those ships that were at least 20 years of age could be replaced. Hughes would also suggest that many older ships be scrapped outright so that specific tonnage limitations could be met by the nations involved. The priority for ships to be scrapped was based on age, so a lot of older ships, many of which were by 1921 of dubious military value would be first on the chopping block. This list would include many pre-dreadnought ships that were still technically in the navies around the world. All of these provisions were, for the most part, expected by all participants, and were really the basic outline of what everybody expected an agreement to be. But Hughes also had an announcement that made it clear that the United States was not just taking naval limitation seriously, but that it was prepared, as the nation with the largest construction program underway, to make monetary sacrifices. Hughes announced that all 15 capital ships that were currently under construction in the United States, 2 of which had already been launched, and several of which were over 80% complete, would all be scrapped. This, when combined with the 15 pre-dreadnought ships that would also be scrapped represented almost 850,000 tons of naval displacement to be destroyed by the United States, a colossal amount. This was a statement about the lengths that the United States was willing to go to to make sure an agreement was reached. Hughes also proposed that the British and Japanese take similar strides to cancel all existing construction plans and to scrap ships that were already being built. All of this scrapping would result, as suggested by Hughes, in the United States retaining 18 capital ships, Japan 10, and the Royal Navy 22, with the British allowed more total ships because, to put it simply, their ships were very old. Hughes’ introduction to the conference set the ton for the negotiations, and many of these initial points would see their way through the negotiations. It also kind of backed the British and Japanese into a corner, because while there were details to be determined no other government could claim that it was the United States that refused to make sacrifices to ensure an agreement was reached.

According to Yamato Ichihashi, Kato Tomosaburo’s translator, Hughes’ speech “electrified the calm session. Some were shocked, some were even alarmed, but the others were pleased.” Kato would then decide that Japan had no option but to accept Hughes’ suggestions, at least in principle, saying “It is simply impossible to oppose the American plan. If we oppose it, we’ll have to pay a heavy price. World public opinion would not allow it.” During the next session of the conference, on November 15th, Kato would announce that Japan accepted the plan in principle, and that a few modifications would be proposed based on Japan’s security requirements, but that the outline of the plan was acceptable. At that same session on November 15th, Lord Balfour, the head of the British delegation would say that the British government viewed the American proposal with ‘admiration and approval’ and that they agreed with the proposal in ‘spirit and principle.’ The main concerns of the British Naval Officers at the conference were not necessarily the general suggestions made by the Americans, but instead that proper provisions were not made for how old the British fleet was at the time of the agreement, and they hoped to rectify this situation before the final agreement was made.

While the three major nations would all accept the basic outline for discussions the details were of course much more complicated. During these detailed discussions the reasons for disagreements at times spiraled well outside of naval strength or naval security. The best example of this is probably the naval building holiday. Obviously this was a core part of the American proposal, and any limitation treaty had to restrict new construction, however, the British were very concerned about what a naval building holiday would mean for its naval construction industry. Building naval vessels was a huge industry, which the governments around the world poured vast sums of money into every single year, the Royal Navy was very dependent on private shipbuilding companies to construct their large capital ships. If all existing orders were cancelled, and no new orders were placed, these companies would probably go out of business, or at the very least they would let their capital ship construction capabilities go into decay. This was not as much of a problem for the United States which relied far more heavily on government owned shipyard, which would be maintained regardless of whether or not they were needed at the time. The British delegation and government tried to suggest several different schemes to work around this problem. Suggestions like constructing a few capital ships every few years just to keep the yards busy. Their reasoning was partially that it was just as cheap to build the ships as it was to pay the companies to maintain their construction facilities and to pay unemployment to the workers, and it would prevent the entire system from going into decay for a decade which would require another large amount of money to gets construction started back up again. Eventually, all of these schemes would be rejected, and due to other concessions that were given to them along the way the British government was unwilling to make these concerns any real sticking point to prevent them from supporting the treaty.

One of the first sticking points for the Japanese related to their very new, and not yet complete battleship the Mutsu. The Mutsu was the second Nagato class battleship, and one that was suggested by the United States as a candidate for scrapping. The Japanese were very resistant to this idea, because of the expense of the ship, but also due to how the ship had been funded. The Mutsu had been partially funded by donations gathered by schoolchildren, which was maybe the best possible excuse for why the Japanese Navy did not want to destroy the ship right before it was completed. The Japanese would dig their heels in about the Mutsu, but the British would help to find a compromise that would allow the conference to continue. The resulting compromise would allow the Japanese to keep the Mutsu, and the United States would get to keep two of the Colorado class battleships that were very near completion. In both cases an older battleship would have to be scrapped to keep the ship ratios correct. The British did not have two new ships nearing completion, or even ones that were under construction and so they would be permitted to design and build two brand new ships, with the only restriction being that they could not exceed the other clauses of the treaty, which would eventually be a 35,000 ton displacement and 16 inch guns. These two ships would eventually turn into the Nelson and Rodney. As with all compromises, to gain the ability to keep the Mutsu the Japanese had to compromise elsewhere, and in this case it was with the ratio of ships that Japan would be allowed to build in comparison to the other navies. The Japanese would agree that perhaps they did not need as many ships as the British and Americans, after all those other navies had to maintain their strength in multiple different oceans. However, the initial negotiating position of the Japanese was that they wanted a 70% ratio. This ratio became a real line in the sand for the Japanese officers who did not even really want to be entering into limitation treaties in the first place, and so it was generally important for the delegation to try and stick to that number. However, this number was totally unacceptable to the Americans. A 7:10 ratio, it was believed by the United States Navy, made any attempt at an offensive action into the Western Pacific by the United States Navy a suicide mission. It was considered to be so in favor of the Japanese that the Americans believed that it was better to not have any treaty at all than one that allowed a 7:10 tonnage ratio for the Japanese Navy. The two sides were at an impasse, which is where the Mutsu came into play. Part of the Mutsu agreement was that the Japanese would agree to a 60% ratio, which is why the Americans and the British got two new ships to the one new ship that the Japanese could keep. This was seen as an important compromise for the American delegation, although it would prove to be of dubious value in later years due to advances in other forms of naval technology.

Another key piece of the agreement, and another which would have drastic ramifications over the next 20 years of naval design and development was the maximum displacement agreed to in Washington. The eventual number that was arrived at was 35,000 tons, which at the time was larger than most capital ships that were being built. Even the Colorado and the Nagato classes were below this number, but they were very close to it, and during the previous 20 years of naval construction ships had done nothing but increase in size. The largest ship in the world at the time was the HMS Hood, which would be over 42,000 tons and it would remain the largest naval ship throughout the treaty period. The 35,000 ton number was in some ways just picked almost at random, there was not some large study done on the best displacement for a capital ship, or any other logical reason that the number was first suggested, it was just larger than most of the other ships that existed at the time. The British wanted the number to be larger, and they would suggest 43,000 tons as a good displacement, which was of course right around the displacement of the Hood. the limitation to 35,000 tons would have drastic ramifications on capital ship design over the next 20 years as navies around the world would try to make the correct design decisions that balanced speed, protection, and armament. Interestingly enough even though all of the navies agreed to this figure very few ships would actually be built within these constraints. The Japanese would not build another class of capital ships until they exited the Washington agreement and started on the Yamato class, which would be almost twice as large. The Americans would build only 6 ships that would nominally obey the restrictions in the South Dakota and North Carolina classes. The British would build the Rodney and Nelson, before abandoning the restrictions late in the design finalization of the King George V class. It is also important to note that when determining the displacement of the ships the nations agreed to use a new standard displacement calculation. Up until this point the navies had all used slightly different formulas when calculating their ship displacement. This could revolve around very simple differences like one nation including the displacement of ammunition and fuel oil used by the ships while others did not. Eventually the nations would agree to a new definition to be used when calculating that 35,00 tons. A basic load of ammunition would be included, around 100 rounds per gun, and all other stores necessary for a voyage like food, water for the crew, equipment, etc. However the number did not include fuel and feed water for the boilers. This was very important to the Royal Navy because they greatly valued range in their capital ships due to the geographical distances that they would have to traverse, whereas other nations generally put far less importance on capital ship endurance.

While capital ships were the primary topic of conversation at the conference other classes of naval vessels were also discussed. There would be limits placed on aircraft carriers and cruisers, both of which we will discuss in greater detail in later episodes. Submarines would also be discussed, with the British and Americans hoping to see their numbers greatly reduced, or at best completely outlawed. It would be in this category of vessel that France would have their greatest influence at the conference. France would accept the 50% displacement quota that they were given for capital ships, but only if they were given the full ability to build submarines, which they saw as the great equalizer against the larger navies of the world. Eventually the British and the Americans would give into this demand, if only because it was seen as important not just by the French but by just about every other smaller naval power in the world. Another clause that would be included in the treaty was that no nation could fortify or build new naval bases on any islands in the Pacific with the exception of Singapore, Hawaii, and islands very close to the Japanese home islands. This was thought to be an important feature by the Americans and the British, and Kato Tomosaburo would get the approval for the clause among the Japanese delegation. This was partially accepted due to how flimsy the clause was which mostly came down to the fact that it did not properly define what was considered a fortification. It also very specifically said that naval bases could not be built on the islands, but it said nothing about airfields and other non-naval focused bases.

After the treaty was signed on February 6, 1922 the reactions around the world were varied. When news reached Japan that the agreement had been reached there was some cause for concern. Two of the primary goals of the Japanese Navy going into the conference had been to ensure that they were given at least a 7 to 10 ratio in capital ships in relation to the United States and to make sure that the long standing goal of an 8-8 fleet, or a fleet with 16 capital ships was not hindered. After the delegation returned to Japan Kato Kanji began to fan the flames of resentment among those Japanese naval and political leaders that favored a much larger Japanese fleet. This would cause a rift between the pro-treaty and anti-treaty supporters within Japan. When Kato Tomosaburo died of cancer during the summer of 1923 the pro-treaty side would lose its most prestigious and influential leader, and Japan would begin the slow slide away from the treaty until it eventually exited the naval agreements altogether in 1935. In London the agreement was reacted to in a similar way by some members of the British government. The Royal Navy’s dominance of the world’s oceans was a tradition that dated back over a century, and so formalizing an agreement that made it clear that Britain was no longer the most powerful naval power, and that it did not have a navy second to none, was difficult for some to accept. However, there was a much greater number of individuals who fully understood that the Empire was not in any economic position to participate in a naval arms race, and so they welcomed the new treaty and the boost to Anglo-American relations that it might result in. As we move forward with this podcast the effects of the treaty will be a constant feature of our story. Nothing would be the same among the three major naval powers around the world, previous plans were cancelled, restrictions were not in place for future building and there were also features of the treaty that would cause some very interesting events in naval design, construction, and planning. One of those events will be the topic for our next episode, and it will be the design and construction of what would come to be known as treaty cruisers, or cruisers that met the 10,000 on displacement limit and the maximum gun size of 8 inches that was agreed to in the Washington Naval Treaty. The construction of these cruisers would result in a naval arms race all of its own, jut not around capital ships, and it would be an important part of naval relations between the three nations before it was addressed at the London Naval Conference. However, I do have to end this episode on the Washington Naval Conference by once again saying that the conference and the treaty were a massive success, not a perfect success, but an important one that would result in its core goal, a drastic reduction in the construction of the largest class of naval vessels. As for why it was a success when so many other disarmament and arms control negotiations during the interwar years would fail, well here is Admiral Kato Tomosaburo himself with one possible explanation. “The conference succeeded because the participating nations agreed on the pressing need to establish world peace and alleviate the burden [of armaments]. And these two aims can be accomplished only by freeing ourselves from the old system of exclusive competition among the powers and by creating a new world of international cooperation.”