Although war with Italy was averted, European war was increasingly possible, presenting a horrific nightmare in which Britain might have to fight Japan and a European power (probably Germany and possibly Italy as well) at much the same time. Throughout the late 1930s, the Admiralty’s only solution was to fight and defeat the Japanese fleet first, then swing the British fleet back to Europe to face the less powerful fleets there. The opposite sequence did not bear thinking about, because war in Europe would exact attrition and might also occupy so much of the fleet that it would be badly outnumbered in the East – which was exactly what happened.
In 1937–9 the Spanish Civil War demonstrated that in European waters aircraft were an effective anti-shipping weapon, perhaps on a par with (or more dangerous than) submarines, because land-based aircraft would often be within range of shipping and because Asdic (sonar) was thought to have largely solved the submarine problem. From 1937 on considerable effort went into converting warships (and preparing to convert merchant ships) specifically to defend merchant shipping against air attacks. This was apart from the threat, which may not have been appreciated before the outbreak of war, of air-laid mines in harbours. Only the Royal Navy seems to have paid attention to shipping protection against air attack during the run-up to the Second World War. The other major navies concentrated on the air threat to warships.
Anti-aircraft is more than defensive guns. Given limited carrier capacity and a much larger Japanese carrier force, how could the Royal Navy protect itself? The Blackburn Skua was one answer. By dive-bombing it could destroy or at least disable the Japanese carriers and thus gain air superiority. It also had air-to-air capability, but that was a distant second to dive bombing. This Skua is diving with its dive brakes open, in an attitude which would later be called glide bombing. (David Hobbs)
King George V shows the standard anti-aircraft outfit as applied to a first-line battleship at the outbreak of war: a fully dual-purpose secondary battery (in this case of 5.25in guns) and four octuple pom-poms. This was more powerful than that of any other navy: the US standard automatic battery at the time was three or four quadruple 1.1in guns and eight single 0.5in. As in the Queen Elizabeths, all four pom-pom mounts were concentrated in her forward superstructure, each with its own director in a small tub at a higher level. No pom-poms or other anti-aircraft weapons were mounted atop the after superstructure, which at this stage was used for the ship’s boats. The Royal Navy view was that to retain its mobility the fleet had to carry its own ships’ boats. The US Navy set up boat pools at its bases, which enabled it to spread more light anti-aircraft guns over its ships. The Y-shaped structure carried two HA director towers which controlled the twin 5.25in guns on the deck below. Around the base of the main battery director are anti-aircraft lookout sights, used to indicate incoming targets to the Air Defence Officer – a feature unique to the Royal Navy at this time. This air defence platform, open to the sky, was adjacent to the open upper bridge (compass platform) on which the ship’s officers stood, so that the ADO could have immediate access to the ship’s CO. No lighter weapons are evident in the photographs. The design originally called for four quadruple 0.5in guns, but they were apparently eliminated when the turret-top pom-poms were added. By February 1940, plans called for six pom-poms, the other two atop ‘B’ and ‘X’ turrets (rockets were mounted instead when the ship was completed, due to a shortage of pom-poms). Both ships armed with rockets (King George V and Prince of Wales) had them replaced with octuple pom-poms when the latter became available in sufficient numbers later in 1941, and Prince of Wales also had a single hand-operated Bofors on her quarterdeck at the time of her loss (it continued to fire after she lost power). King George V is shown on the voyage to the United States in January 1941 on which Ambassador Lord Halifax was taken to Annapolis, the closest port to Washington. (Naval Institute Collection)
Until about 1936, the Royal Navy expected the major air threat at sea to be against its fleet. Since destroyers were agile, they were unlikely to be singled out for attack, which would be concentrated on capital ships. It followed that a destroyer gun elevating to 40° could usefully support the capital ships. The ‘Tribal’ class was designed specifically for such support, with four twin 4.7in guns capable of 40° elevation. The subsequent ‘K’ and ‘N’ classes had the same gun. An RAN destroyer displays her forward twin 4.7in guns in the Southwest Pacific during the Second World War. (State Library of Victoria)
Caledon, shown here on 1 February 1944, typified the production version of the anti-aircraft (shipping protection) cruiser, armed with standard guns (such as the twin 4in). In 1940 the US naval attaché in London reported that anti-aircraft cruisers were ‘worth their weight in gold’. The US Navy accordingly began to plan a comparable conversion of Omaha class cruisers, to be armed with 5in/25s, but the outbreak of war precluded it.
Initial Approaches to the Fire-Control Problem
The Royal Navy committees to capture wartime lessons included a Naval Anti-Aircraft Committee convened in 1919.1 The anti-aircraft committee decided that all of its experiments should employ director firing (a new departure for air defence) because this method ‘presents unquestionable advantages over individual firing: greater accuracy, greater rapidity, more continuous firing and simpler control’.2 It was not clear whether an anti-aircraft director should incorporate a rangefinder; in 1919 the Royal Navy was integrating its surface directors with rangefinders because wartime experience suggested that otherwise fire-control systems might suffer when rangefinder and director pointed at different targets. For the moment, the Committee was willing to use separate director and rangefinder for experiments. In 1924 arrangements were made to install high-angle directors and separate rangefinders on board capital ships.3 The complexity and awkwardness of existing anti-aircraft fire control made it obvious that calculation should be automated. In addition to aiming guns, the fire-control computer had to calculate fuse settings. Other navies reached the same conclusion.
By this time the RAF had taken over the wartime Royal Naval Air Service. Although not a significant factor in 1918–19, attempts by the new Royal Air Force to shoulder the navy aside became an important factor in Royal Navy views on naval air defence (among many other things). Leaders of the new RAF (and, for that matter, of air services abroad) liked to claim that their inexpensive force made expensive surface navies obsolete. Thus on several occasions between the wars the Royal Navy found itself compelled to explain to the Cabinet why it considered large warships, particularly battleships, viable in the face of air attack. The navy’s need to take air attack into account may explain why the Royal Navy was better equipped for air defence than its contemporaries. In the 1930s the Royal Navy was well on the way to having the heaviest existing anti-aircraft batteries, including the world’s heaviest batteries of light automatic anti-aircraft weapons. War experience was to show that even these batteries were insufficient against the new threat. It was a great wartime disaster that, having provided so much anti-aircraft firepower before the war, British warship designers had not provided much margin for further increases.
Because it believed that several aircraft would have to be devoted to any first-line warship target (using level and torpedo bombing), the Royal Navy assumed that attacks on the fleet would concentrate