The Treaty Mirage
History of Naval Warfare, Part 13
As late as 1939, it was still possible for a citizen of Great Britain to take a global voyage and take pride in the readily apparent trappings of Britain’s global power. Boarding a steamer in Bombay, he might take a long voyage past a variety of critical global chokepoints and bases - crossing the Indian Ocean to Aden, sailing up the Red Sea through the Suez Canal, stopping over at Malta in the Mediterranean before passing through Gibraltar, and then reaching home in Southampton - and along the way he would have seen nothing except British bases, British ships, and British power.
This was a centuries old system of geopolitical power projection, preserved very carefully to give the impression of a stable and predictable world. The essence of this system was very simple: this was a Eurocentric (and I use the word without the pejorative connotation) world system in which sea power was the medium of global influence, and the main way to measure that influence was in battleships and the bases that allowed them to operate at vast distances. In other worlds, the scenes that awaited our passenger were largely unchanged from the 18th Century. Sailing ships of the line had of course given way to the steel of the big-gun battleships, but the axis of global power was still a network of British naval bases occupied by British capital ships. The world’s other sea powers had the capacity to project force regionally (Japan in East Asia, Italy and France in the Mediterranean, and so forth) but only Britain was everywhere, all at once, with big guns.
By 1950, this world would be unraveling on virtually every level. Enumerating the many ramifications of the Second World War is a monumental task, but when it came to sea power the result of the war was fairly simple: after generations of British supremacy at sea, World War Two destroyed (either completely or practically) virtually every naval force of consequence in the world with the exception of the American Navy, which grew exponentially and came to predominate absolutely. On the eve of the war, in 1938, Britain was still widely recognized as the greatest sea power in the world, but there were no less than six navies of either real or potential consequence regionally. By 1945, however, the board had been swept so clear of competitors that the American Navy was now not only more powerful than any rival, but more powerful than all the rest of the world’s navy’s combined. Having lost is position at the apex of the naval power structure, the rollback of Britain’s imperial infrastructure was sure to follow.
In short, our fictional passenger voyaging from India to England was passing through a a world which gave the impression of continuity and stability across centuries, but which was in fact on the verge of total collapse. The physical experience of sailing from India, through the Suez, past Malta and Gibraltar, and then on to England, Canada, or the Caribbean - transiting thousands of miles and seeing only British battleships in British harbors - reflected implicit underlying assumptions about the world: a hierarchy of state power predicated on sea power, in which Britain sat at the apex and status was largely measured in big gun battleships. All of these assumptions were ripped apart by the Second World War. It was not only that Britain lost her spot at the top of the hierarchy, but that the hierarchy itself largely ceased to exist; America did not simply move ahead of her rivals, but came to overpower the notion that she had any rivals at sea at all. From 1945 onward, a pivotal reality of world affairs was the fact that only the United States could project force by sea and air anywhere in the world, almost with impunity. The United States Navy was not only the strongest force anywhere in the world, but the strongest naval force everywhere, all the same time. It was the destruction of all potential rivals in the Second World War that made America, in the second half of the century, the single most powerful state that has ever existed. Furthermore, the old currency of sea power - armored battleships fighting with lung range naval gunnery - came to be radically overshadowed by new platforms which had finally reached technical and tactical maturity, like submarines and naval aviation.
What made the interwar period odd was not simply the fact that it presented a false mirage of stability, but also that there was a conscious effort by naval policy makers and statesmen to suspend the situation and hold it in stasis. Naval construction was regulated by treaties which aimed to not only preserve the relative status of the sea power hierarchy - allocating specific shares of battleship tonnage to create a carefully calibrated naval balance of power - but also explicitly rated and regulated sea power in terms of battleships.
On the eve of war in 1939, then, sea power resembled a living relic of a dying past: a fossil of a passing age, waiting to be smashed on a technical, tactical, and geostrategic level. Until the bombs began to fall, however, they gave a continued impression of life. Few suspected that big gun capital ships, long the accepted currency of global power projection, were on the verge of tactical obsolescence, and fewer still could have predicted that the global network of European naval bases - keystone positions like Singapore, Dakar, Malta, Saigon, and Aden - were about to be wiped out. In real time, it is surprisingly hard to tell when one era is ending and another is beginning.
Freezing the Fleets
The Second World War carries the unusual distinctive of containing with in it two separate wars of different sorts, both of which were the largest conflicts in history of their respective types. In Europe, the Nazi-Soviet War was by far the largest and most destructive land conflict in history, while the Great Pacific War, fought by the Imperial Japanese and American navies, was the largest naval conflict ever seen, both in the scale and destructive power of the fleets and the colossal distances involved. There is, however, a relatively curious disconnect in the preparatory intensity. The Nazi-Soviet War was anticipated by intensive rearmament programs by both Germany and the Soviet Union, as both Hitler and Stalin scrambled to arm themselves to the teeth with modern weaponry. In the Pacific, however, there was nothing that can be deemed a proper arm’s race. In fact, rather the opposite was true, and in the interwar period the navies of the world were regulated by a deliberate global program of naval arms control.
It is perhaps a bit counterintuitive and ironic that history’s largest naval-amphibious conflict was preceded by a long period of negotiated arms control and limited naval construction, but there was a fairly straightforward logic to the program. Naval building lent itself to an attempt at negotiated control, because the totem items - particularly battleships - were very expensive, had long construction timetables, and were relatively easy to count for purposes of compliance verification. Limiting capital ship construction therefore had strong appeal as a way to control costs - and this was very appealing indeed to governments that were cash strapped from the Great War - and the relative ease of counting ships and verifying tonnage limits meant that agreements could be entered into with some degree of confidence that they would be honored.
A further curious element of interwar shipbuilding was the fact that every navy of consequence, either globally or regionally, belonged to states that had been allied in the Great War. In the interwar period there were exactly five navies worth considering, belonging to Britain, the United States, Japan, France, and Italy. To this extremely limited and exclusive club, Germany and the infant Soviet Union had to be added as states that were theoretically capable of fielding battlefleets, though in the interwar period they were unable to do so owing to the general collapse of their power in the aftermath of World War One. With only five powerful fleets afloat, and two potential additions at a much later date, it proved relatively straightforward to codify the relative balance of power on the seas.
The outcome which emerged from this milieu, in which both public aversion to militarism and the need of governments to restrain spending, was an entirely novel arrangement of negotiated restraint known simply as the Washington System, after the Washington Naval Treaty, which was signed by the British Empire, the United States, the Japanese Empire, France, and Italy on February 6, 1922 in Washington DC. The drafters and signatories were rightfully proud of what they had accomplished, which was accurately hailed as the most comprehensive and ambitious arms control treaty ever devised.
What stands out about the Washington Naval Treaty was not simply that the five remaining naval powers of the world agreed to limit their construction programs, but they did so in an unequal manner which aimed to explicitly enshrine a particular balance of power in the world. The essence of the treaty was a threefold restriction on capital ship construction, which established limits on both the total tonnage of capital ship fleets and the tonnage of individual ship classes, while stipulating a “naval holiday” of ten years in which no existing capital ships could be replaced. The holiday was later extended by five years at the 1930 London Naval Conference, so that for the majority of the interwar period there were no new capital ship classes launched. The net effect of this was to cap both the aggregate size of battle fleets and the size of their constituent ships, while also temporarily freezing modernization by delaying the rollout of new classes.
Remarkably, however, the parties that convened in Washington agreed to a disproportionate allocation of naval power which explicitly created something like a formal geopolitical system of sea power. Under the Washington System, in essence, the US Navy and the Royal Navy were each given about 30 percent of the world’s battleship tonnage (and by extension firepower), while the Japanese got 20 percent, and the Italians and French got 10 percent each.
The allocation of total tonnage, combined with limits on the maximum tonnage of individual warships, synergized to create extremely transparent arithmetic governing the numbers of warships in the relevant fleet. Because battleships were capped at 35,000 tons of displacement, the 525,000 total tons allocated to the US and Royal Navies meant that they could possess fifteen large battleships each, while Japan’s 315,000 total tons allowed for nine. In order to come into compliance with the tonnage limits, both the British and the Americans were forced to scrap many of their older dreadnought and pre-dreadnought battleships, and the British had to conduct a redesign of their new Nelson-class to slim her down.
The allocation of tonnage was an attempt to formally recognize the variegated strategic needs of the treaty parties, while accepting the realities of the extant balance of power. The United States and the British received disproportionate tonnage allocations as the two powers with truly global commitments: the US Navy with its two oceans, and the British with their global chain of bases. Japan, as a “single ocean power”, received a healthy allocation, while the French and Italians were balanced against each other as regional rivals with equal tonnage. The Washington System therefore presented a concrete understanding of world affairs with the following picture: two large, essentially equal global Anglo-American navies, a Pacific power in Japan which was not so far behind the world powers, a pair of mid-sized Mediterranean navies in France and Italy, and a humiliated former naval power in Germany.
Judged purely as an instrument for putting a much needed brake on the growth of the world’s battlefleets, the Washington system was an unbridled success. After decades in which battleships had been continuously laid down while growing larger and larger, the treaty era locked naval construction in stasis, as if the party navies had been flash frozen. More than a decade passed between the design of Britain’s 1922 Nelson class battleships (the last of the pre-treaty classes) and a wave of post-holiday classes designed in the late 1930’s, including Britain’s King George V, the French Richelieu, Germany’s famed Bismarck, and the Japanese Yamato super-battleships.
The point at which we are driving, more broadly, is that the treaty era worked to temporarily preserve the impression of global British supremacy, allowing our fictional voyager to experience the world of his grandfathers, circuiting the world and seeing only British battleships in British bases. Britain’s position atop the world was preserved not only due to the explicit tonnage ratios of the treaty system, but also due to the geostrategic disposition of the other parties. The United States, for example, was granted an equal tonnage to the Royal Navy, but America’s return to an insular stance following World War One worked against robust American construction. Consequentially, by the time the treaty system expired, the US Navy was actually below its allocated tonnage total.
Geostrategic interests around the world dovetailed to create the impression of British supremacy. Japan was clearly an ambitious, revisionist power, but she was contained to East Asia for the time being, and pouring ever greater resources into a continental strategy predicated on the Asian mainland. America’s voluntary return to a reclusive foreign policy left her underweight. Closer to home, the French and Italian navies were thinking almost exclusively in reference to each other - indeed, the Italian navy was by far the most modern and professional arm of the Italian military, and was designed specifically for a scenario in which Italy would fight France for control of the western Mediterranean without the involvement of the Royal Navy. Thus, although British power projection faded east of Singapore, there was no discernable reason to believe that the core nodes of the imperial system were threatened.
Planners in all of the world’s great navies made miscalculations with varying levels of consequence and egregiousness. Virtually all, with the exception of Japan, would come to lament that their post-treaty battleship designs were not all ready for action in 1939. Admiral Raeder, in Berlin, trusted Hitler’s word that war would not come so soon, and was thrust into action with a half fleet. The British, for their part, were taken aback by the rapid fall of France, which gave the German submarine fleet an easy access to the Atlantic which had been lacking in the previous war. As for the American and Japanese miscalculations, they are well known and need no enumeration.
The point was not that the treaty era successfully prevented war, as it plainly did not and could not. The treaties did, however, fill an important role in the interwar context. Domestically, governments faced both financial pressure to control their armaments budgets as well as pressure from a public opinion that had turned, sharply in many cases, against militarism. The Washington Naval Treaty and its London addendum created an explicit answer to these pressures, while also apparently offering an acceptable balance which considered the relative force generation needs of the powers. Britain and the United States, with their commitments in multiple oceans, could take comfort in the superiority granted to them in the treaties. As for Japan, their fleet could muster perhaps 70% the strength of the Anglo-American fleets, but this was a number that they could live with for a time on the basis that neither the Royal Navy nor the US Navy could be expected to concentrate all its strength in the East Asian theater.
This created the illusion of at least a tenuous stability, but above all it allowed material strength to be inventoried and assessed in a relatively transparent and uniform way. The basic currency was battleships, but other ship types - like destroyers, cruisers, and submarines - were well understood, filled discrete roles, and could be counted with relative ease. What stands out most about the treaty system was that it created a balance sheet of combat power that was apparently very easy to understand.
What was not well understood was that not only was this tenuous balance of power about to be smashed by the revisionist states - Germany and Japan, above all - but also that the measurement system upon which this balance rested was about to be bashed into total obsolescence. Interwar planning was based on inventories of capital ships and the expected strength of the main battle line. In Japan and in the United States, there was talk of fighting a “second Jutland” in the Pacific: a titanic duel of naval gunnery, in the tradition of Tsushima and Trafalgar. The Admirals would get something like what they were expecting, and the looming Pacific War would be intensely battle-centric - but it would be the carriers that would decide the outcome.
The Rising Sun: Japan and the Carrier Revolution
It is a trivially obvious point that aircraft carriers became pivotal, defining weapons systems in the eventual Pacific War between the Japanese Empire and the United States. Their potency was underscored from the outset by the Japanese attack on Pearl Harbor, which demonstrated the unprecedented striking power of naval aviation, and in the years to follow the aircraft carrier has become the seminal American weapons system: America’s naval supremacy was achieved by winning the world’s first and only great carrier war, and American power projection today finds its most imposing and infamous form in its carrier groups, which give the US Navy the unique ability to bring colossal kinetic power to bear almost anywhere in the world.
Indeed, the aircraft carrier is such an obviously powerful, expensive, and unique platform for force projection that it seems trivial to us that naval aviation should have created a total revolution in naval combat, but that was not at all immediately obvious to admiralties in the interwar period. It was, of course, obvious that naval aviation would play an important role in future conflicts, but the idea that carriers would almost immediately push big gun battleships into near total obsolescence was widely viewed as absurd. Carrier design, theories of carrier operations, and the tactics of naval operations instead followed in incremental evolution during the interwar period, advanced largely by the Japanese and American Navies, which saw the carrier take the leap from an ancillary ship type to become the keystone kinetic platform.
Naval aviation was still in a decidedly rudimentary state when the Great War ended, with allied navies - primarily the British - operating a handful of improvised carriers and seaplane tenders, which served mainly as reconnaissance systems. Carriers only began to proliferate during the treaty era due to provisions which allowed battleship hulls which were then in progress to be converted into carriers. Japan’s Akagi and Kaga and the US Navy’s Lexington and Saratoga were among the fleet carriers to be built out in the treaty area on hulls intended for battlecruisers. Aircraft had not yet demonstrated any ability to deliver firepower even remotely on par with the powerful naval artillery of the day’s capital ships, however, and so initial theories of carrier operations centered on the potential for aircraft to magnify the firepower of the main battle line. Due to the small numbers of carriers that where then in service, these theories were mainly worked out on tabletop games rather than through fleet exercises.
In the 1920’s, during the treaty era, Japanese thinking began to converge on the expectation of an “air battle” over the battle zone of dueling surface fleets. This line of thought predicted that, in a future clash between battleship fleets, aircraft would serve a critical role as spotting platforms, providing an eye in the sky to dial in the accuracy of the fleet’s big guns. As naval gunnery was by now designed to operate at extreme ranges which strained even cutting edge shipboard optics, the advantage of maintaining a screen of spotting planes over the battle zone was obvious. Per the Japanese thinking, therefore, the side that could control the sky over the surface battle would enjoy significantly better gunnery and so be expected to prevail in the artillery duel. If you had asked a Japanese admiral in the mid 1920’s, then, what the role of the aircraft carrier might be in a future fleet engagement, he would have suggested launching fighter aircraft to chase away enemy spotting planes while protecting friendly spotters, expecting that the side which won control of the airspace would enjoy more accurate and thus more deadly gunnery as a reward.
The theory that control of the airspace above the gunnery battle would provide a potentially decisive advantage naturally gave way to the next stage in thinking about naval aviation, in which it could prove decisive to attack the enemy’s carriers at the outset of the battle and so gain control of the air from the very beginning. The hinge element here was the relative vulnerability of aircraft carriers to air attack. In the early 1930’s, it was hardly expected that aircraft would be able to easily sink or neutralize heavily armored battleships. Carriers, however, did not need to be sunk in order to be neutralized as combat assets: simply dealing enough damage to the flight deck and hanger facilities to prevent the enemy carrier from launching its planes was enough. In this operational sketch, Japanese carriers would launch an attack on enemy carriers at the outset of the battle, striking their flight decks to either delay the enemy’s launch or prevent it outright. Having seized control of the aerial battlespace from the beginning, Japanese fighters and spotters would therefore be free to loiter over the gun battle and range in the fire of Japanese battle line.
The Japanese were hardly alone in reaching such a conclusion. As early as 1921, the US Naval War College had similarly determined that sinking or neutralizing enemy carriers at the outset of battle was the bet way to achieve air control over the battlespace; as in the Japanese case, however, this was viewed as desirable as a means to provide spotting for surface gunnery. While battleship enthusiasts continued to dominate in both navies (the so-called “gun club”) it is notable that by 1930 theorists in both the Japanese and American fleets had come, with varying levels of commitment, to believe that preemptive attacks on enemy aircraft carriers would be a decisive element of battle.
The question then becomes, rather plainly, why was it the Japanese - much the poorer and less industrialized power - that first and most fully developed the massed carrier packages which would prove so decisive in the Pacific? The reality - and the paradoxical point at which we are driving with this entire discussion - was that the development of Japan’s massed naval aviation utterly upended interwar calculations about naval power. The Washington System of the treaty era had been designed to calcify a perceived hierarchy of naval power which put the Anglo-Americans at the apex, but this hierarchy was explicitly measured in battleship tonnage. Judging purely on the weights and inventories of the battlefleets, the Royal Navy justified its self-perception as the most powerful naval force in the world. In reality, however, by 1941 the Japanese Naval Air Arm constituted the single most powerful offensive asset fielded by any of the world’s great navies.
Japan’s path to developing the world’s most formidable naval striking force was characterized, unsurprisingly, by a unique admixture of theory, material opportunism, and combat experience which in this case took place in China. In this case, the problem was particularly multivariate, because it required not only the development of the carrier fleet and appropriate tactical systems, but also the aircraft and pilots required to make them work.
Japan’s aircraft carriers of the Great Pacific War were predominately an offensive weapon, capable of projecting enormous striking power over long distances. Nevertheless, Japanese naval aviation was animated at first by problems of a defensive nature. The question, very simply, was how Japan might be able to prevent an adversary from bringing his own battleships and aircraft carriers right up to the littoral of the home islands. In early 1930, Commodore Toshio Matsunaga (then an officer on one of Japan’s first carriers, the Akagi) penned an article in the naval journal Yushu, which argued that long-ranged, land-based bombers could fill an essential defensive role by allowing Japan’s ground based aviation to attack, attrit, or even destroy an incoming enemy fleet while it was still at sea. He argued - hyperbolically, but still in a generally correct direction - that an adequate force of long ranged bombers operating from the home islands, supplemented by a handful of aircraft carriers, would make Japan nearly impossible to invade.
