One of the more enduring images of Second World War naval warfare is of a ship defending herself against hordes of air attackers. The US Navy, the Royal Navy and the Imperial Japanese Navy found themselves under particularly heavy air attack. This book is the story of how that defence was developed and of how well it worked for the different major navies. Post-war developments indicate the conclusions the major navies drew.
This story would make no sense without taking into account the impact of the Great Depression. For the United States, the Depression began in 1929, and it did not really end until the country mobilised for the Second World War beginning in 1940. Attempts at recovery beginning in 1933 included some new construction, but always under tight economic conditions which limited what else could be bought. That is a major reason why the US Navy was so very under-armed in light anti-aircraft weapons in 1940. The country was fortunate that it could mobilise, even if incompletely, before it had to fight. More money was available before the 1929 Crash, but successive administrations considered military and naval spending a drag on the economy. In retrospect that was no very bad thing, because heavy spending in the 1920s would have produced large quantities of obsolete equipment. Aircraft were changing far too rapidly, particularly in the 1930s.
Rapid pre-war expansion brought its own problems. The navy found itself flooded with new personnel, who had not received extensive training in technical schools before encountering such increasingly sophisticated equipment as the Mk 37 fire-control system. Exercise scores fell, even though targets did not change very much between 1939 and 1941. Again, fortunately for the United States, much of the necessary training was completed by the time war broke out – when even more new sailors arrived.
The situation in the United Kingdom was more complicated. Before the First World War the Royal Navy was clearly the most advanced in the world, and during the war it gained far more experience than its rivals. Despite the crippling cost of the war, it was able to continue development after the war. It also had an enormous overhang of existing modern ships, so new construction was not too urgent during the 1920s. Beginning in 1919, the British adopted the ‘Ten Year Rule’ for planning, the assumption that they would not face a major war for a decade. By 1929 it had been made self-perpetuating. Initially the rule was probably mainly a way of emphasising the need to modernise in view of changed orientation (towards a Japanese threat), but ultimately it became a way to cut expenditures so as to promote economic recovery from the remaining damage done by the First World War. Ultimately the effect of the Rule was to cut expenditures on expendables, such as shells and fuses. Thus, when the situation was reversed and the initial recovery programme concentrated not on ships or guns but mainly on items such as shells and fuel reserves and quartz for sonar transducers.
As in the United States, the effect of the Depression was to limit new production, although work on prototypes continued. Unfortunately the British felt constrained to mobilise much earlier, because the Japanese advance in the Far East threatened them more directly. The ‘Ten Year Rule’ was dropped in 1932, and by 1934 a Cabinet committee originally formed to develop disarmament policy had been transformed into the Defence Requirements Committee (DRC), responsible for making up deficiencies accumulated under the ‘Ten Year Rule’. At about the same time, before Hitler rose to power in Germany, some in Britain saw Europe skidding towards war. That was another reason to repair deficiencies in defence, but it also greatly complicated the British position – the country faced war both in the Far East (which the Royal Navy had long envisaged) and in Europe. The Royal Navy formulated its anti-aircraft rearmament programme in 1936, after the shock of nearly having to go to war with Italy over the Abyssinian (Ethiopian) Crisis.
From an air defence perspective, mobilisation (or rectification of deficiencies, as it was initially) meant that the Royal Navy had to continue to produce existing weapons and fire-control systems, whatever their deficiencies: the iron law of mobilisation is that you produce what is on hand – you do not wait for something better. The Depression compounded the problem by dramatically shrinking the British industrial base. As the country recovered in the mid-1930s, its industrial pattern changed away from what the Admiralty had previously relied upon, so it became more difficult to build back-up. Developing entirely new systems while mass-producing existing ones was less and less possible. That is why the Royal Navy entered the Second World War with totally inadequate high-angle control systems. It had no real alternative. The navy and its ordnance organisation knew what was happening, but that did not really matter.
The Royal Navy’s view of ship design requirements also had a considerable impact. Given the worldwide empire, the Royal Navy always had to take the need for numbers into account. The Admiralty generally equated ship size with cost. Cruisers were a particular problem. In the 1920s the Admiralty estimated that it needed seventy cruisers. It found the new 10,000-ton ‘Treaty Cruisers’ ruinously expensive, and British delegates to the London Naval Conferences of 1929 and 1935 sought to curb the size of foreign cruisers so as to make the desired number of British cruisers affordable. The 1930 London Naval Treaty prohibited further construction of cruisers armed with 8in guns, but at a high price: the Royal Navy had to agree to near-parity with the United States, which did not have a global empire and needed many fewer ships. The British believed that rational foreign navies would be satisfied with cruisers about the size of its Leanders, about 7000 or 8000 tons rather than 10,000 tons. They were shocked when the US and Imperial Japanese Navies both laid down much larger ships. The British felt compelled to build their own large cruisers, the ‘Town’ class – which they could hardly afford in sufficient numbers. They finally solved the problem in the 1936 London Naval Treaty, which limited future cruisers to 8000 tons. Only the British actually built ships of this size, the Fiji class. The US Navy designed an 8000-ton cruiser (CL 55), which led it to design a dual-purpose 6in gun as armament, but once war broke out in 1939 the treaty was considered defunct, and the CL 55 actually ordered was the 10,000-ton Cleveland.
Anti-aircraft guns in action: 4in Mk V HA guns on board the Australian cruiser Sydney. (State Library of Victoria)
All of this had painful implications for the Royal Navy. The Fiji design packed the armament of a 9100-ton ‘Town’ into an 8000-ton hull. The ‘Town’ had a heavy anti-aircraft battery by pre-war standards, but early war experience showed that those standards were grossly inadequate. Unfortunately the ‘Towns’ and other British warships turned out to be too tightly designed to accept much additional light anti-aircraft armament without considerable sacrifices. The British experience contrasts with that of the US Navy, which managed massive increases in light anti-aircraft weapons as the war progressed. It is possible, too, that British standards of stability prohibited anything on the US scale; the Royal Navy often operated in rougher waters.
Money was too short between the wars to replace the obsolete Mk 19. The best that could be done was to combine it and a new stereo rangefinder on a single enclosed mounting, which was called Director Mount Mk I. It was installed during 1939–40 on board US battleships and cruisers. The boxy director mountings are evident fore and aft on board Northampton, photographed in Brisbane between 5 and 10 August 1941. The opportunity was taken not only to integrate rangefinders and directors, but also to move the directors to the centreline, where they had much better arcs (later cruisers had directors on the centreline). Modernisation included doubling the medium-calibre anti-aircraft battery to eight single guns, the number in later cruisers. As early as 1937, the US Navy planned to modernise its newest battleships (the ‘Big Five’) with newer Mk 33 directors, which were considerably