yet they were probably unaware of the integrated fuse-setters in the ammunition hoists). The US system included a stable vertical (a vertical reference used to stabilise the director) and RPC for the 5in guns. The British argued, however, that US destroyers were top-heavy compared to their own ships; the US Navy did not contemplate the sort of rough waters the British expected. Nos 3 and 4 mounts were unshielded in order to save weight. Notably lacking was much of an automatic battery to beat off dive bombers. This ship could accommodate a pair of 0.50-calibre machine guns on the platform below the searchlight aft. In 1940 the US Navy doubted that defence against such attack was really practicable; it expected to rely on barrage fire by medium-calibre guns. By December 1940 the Royal Navy was using such ‘umbrella barrages’ in action.
By 1941 the US Navy wanted splinter protection for all its guns. Gleaves, a sister-ship of Hillary P Jones, is shown after a Boston Navy Yard refit, 18 June 1941. Nos 3 and 4 guns are now half-shielded (they have no roofs); full gunhouses would have added too much weight. Note also the gun tubs, for 0.50-calibre machine guns, around her after stack. She had another pair of gun tubs just forward of her bridge structure on her 01 level. Her after bank of torpedo tubes had been removed as weight compensation. The next step was to replace No 3 5in gun with a pair of twin Bofors, from 1942 onwards.
More generally, aircraft were the exception to the slow development of fleets between the wars. In the 1920s and 1930s they were inexpensive, and the potential for development was huge. Particularly in the United States and in Japan, relatively small investments in naval aircraft development had huge payoffs. From the point of view of naval air defence, that meant huge changes in requirements and the obsolescence of earlier systems. Thus the Royal Navy, which had been quite air-minded and had deployed an advanced high-angle fire-control system in the 1920s, found it difficult to devise an entirely new system capable of keeping up with a rapidly-evolving threat in the 1930s. On the other hand, because the United Kingdom developed a large electronics industry between the wars, it was able to deploy radar in quantity and with high quality. Radar in turn made it possible for the Royal Navy to make up for deficiencies in anti-aircraft gunnery by controlling fighters against enemy bombers. The Imperial Japanese Navy had no such potential, because it had spent most of its money on pre-electronic forms of naval warfare.
The limited cost and rapid development potential of aircraft explain why Germany, which created a large military machine so rapidly, emphasised them both ashore and over the sea. For the Germans aircraft were also attractive because most people saw them as the embodiment of the future. Hitler and his Nazis represented themselves as the future of Germany, and it was natural for them to make the Luftwaffe integral with the Party. To some extent Mussolini had a similar view of aircraft and his air force, although the result was less successful than Hitler’s. German and Italian shore-based aircraft were the key elements of the war the Royal Navy fought in the Mediterranean.
During the Second World War it was not well understood that although aircraft might be plentiful, experienced aircrew were not. Only after the war did it become clear how devastating losses could be, particularly if new aircrew were not being trained rapidly enough. Thus after the successful ‘Turkey Shoot’ which wiped out the Japanese carrier air arm during the battle of the Philippine Sea (June 1944), US naval aircrew were depressed because they had not dealt with most of the Japanese carriers – a view which carried over into the success of the Japanese decoy force (consisting of carriers with few aircraft) at Leyte Gulf (October 1944). The Japanese were particularly affected because they had decided against expanding their aircrew training programme. Although most aircraft were shot down by fighters, guns did their share. In the Japanese case, the loss of aircrew led indirectly to Kamikaze tactics. After the bloodbath in the Solomons in 1942–3, few of the highly-trained pre-war aircrew remained. Their relatively untrained successors performed much more poorly, particularly since they faced more and more formidable defences: better US fighters flown by increasingly experienced pilots and directed by radar, plus much more powerful anti-aircraft batteries with better fire control and proximity fuses. When asked after the war to justify Kamikaze tactics, a senior Japanese officer remarked that few aircraft returned no matter what the tactics; better to adopt tactics which promised to achieve something for the inevitable sacrifice. That was apart from the possibility of greatly multiplying the number of attackers by using all available pilots, including partly-trained ones. Those pilots could not have executed conventional attacks.
Details mattered enormously. Most anti-aircraft guns, down to about 40mm or 37mm, were power-worked. If a ship lost power, they were nearly useless, even if they had alternative manual controls (which could not move them nearly fast enough to track targets). After HMS Prince of Wales lost power due to a very unlucky torpedo hit, her powerful light anti-aircraft battery was suddenly reduced to a single Bofors on her quarterdeck and a few Oerlikons. No wonder her gunnery officer thought that Bofors was worth all her pom-poms; but he did not realise that the only way to wield massive anti-aircraft firepower was to accept power operation. The flaw in the ship’s anti-aircraft armament turned out to be the absence of emergency diesel generators, of the type the US Navy and not the Royal Navy provided.
Similarly, the way in which fire controls and associated equipment was connected to guns mattered. Until the 1930s the Royal Navy relied entirely on step-by-step motors to transmit data, for example from a fire-control computer to a gun mount. These devices are simple and robust, but their action is abrupt, as they click from one setting to the next. The Royal Navy seems to have rejected stabilisation in anti-aircraft systems because that required smooth transmission from a stable element to the guns and directors. By the time the Royal Navy had a smooth enough form of transmission (Magslip), it was too late to reverse the earlier decision, because Britain was mobilising.
Pre-war financial restrictions precluded development of a fire-control system for the 3in/50 gun, which armed the ten Omaha class cruisers and the oldest battleships, among others. At best, these ships could only fire barrages through which, it might be hoped, an attacking aircraft might fly. As war came closer, old destroyers like Overton, shown, were rearmed with six 3in/50s – but they too had no special fire-control systems, and to describe them as anti-aircraft escorts was unfortunate at best. As late as 1943 destroyer escorts armed with 3in guns lacked any fire controls.
Much the same might be said of the British decision not to adopt stereo rangefinders for anti-aircraft fire. Coincidence rangefinders, particularly the horizontal ones used by the Royal Navy, proved ill-adapted to anti-aircraft operation. Rangefinding problems helped convince the British to accept what turned out to be a poor high-angle control system, in which target speed had to be estimated on the basis of perceived target type. Only in 1943, with the evidence of US stereo rangefinding before it, did the Admiralty admit that it should have adopted stereo techniques for air defence.
Technical details have been presented to give a clear idea of what the major navies were doing during the supposedly empty inter-war period to protect themselves against air attack. Although their efforts were not entirely effective, it is clear that they were extensive. Details also make it possible to compare different approaches, particularly those of the Royal Navy and the US Navy, in as objective a way as possible. To the greatest possible extent, this material has been taken from contemporary internal documents rather than from later ones.
For continuity, the story of systems conceived before the war has generally been continued into the Second World War in the inter-war chapters, the wartime chapters concentrating on entirely new wartime developments. Thus in the US case the various Bureau of Ordnance machine gun directors (Mks 44, 45, 49) conceived in 1940 are in the pre-war chapter, but the wartime Mk 51 and its ilk are in the wartime chapter. Similar logic applies to the other navies. Except for the US Navy and the Royal Navy, virtually all wartime equipment was of prewar conception and design.
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