One of the mysteries of Britain's fear of the bomber is why it wasn't a fear of the submarine instead. In the First World War Germany attacked Britain directly by air and indirectly by sea, but only the submarine blockade came anywhere close to knocking Britain out. The same was true of the Second World War, though the difference was less, as was the danger. Yet between the wars, it was the air menace which preoccupied the public mind, almost to the exclusion of the sea menace. I came across an article today which, although it doesn't directly address this question, does shed some light on it from the naval point of view: Joseph P. Maiolo, 'Deception and intelligence failure: Anglo-German preparations for U-boat warfare in the 1930s', Journal of Strategic Studies 22 (1999), 55-76.
The simple answer is the British development, mostly after 1918, of ASDIC. This is more familiar to us today as sonar, and in simple terms worked by sending out pulses of sound through the water and listening for the echoes as they reflect off submarine hulls. It promised much greater effectiveness than the passive hydrophones used up until then. The Royal Navy was understandably quite pleased with this and worked on trying to perfect it for operational use, albeit with limited success. What emerges from Maiolo's account is the way in which the Admiralty tried to manage the public flow of information about ASDIC for both domestic and foreign consumption. The point of this was to make foreign powers doubt the usefulness of submarines and so, hopefully, not build them.
ASDIC's existence was a secret for most of the 1920s, for example, but from 1929 the term itself was allowed to circulate publicly, even if not exactly publicised. In mid-1932, the British press reported that the Admiralty was experimenting with a submarine-detecting apparatus that 'spelled the doom of the submarine as an engine of warfare' (59). In 1936, the parliamentary secretary for the Admiralty, Lord Stanley, told the House of Commons that
I hope I am not here betraying any very great naval secret, but it is a fact that we have to-day an almost fool-proof and efficient anti-submarine device. I hope it does not reveal any secret to say that it operates on the system of the reflector ray ... (62)
Such claims were met with some scepticism by naval experts, both in Britain and in Germany, and according to Maiolo the Admiralty learned from this that vague statements placed in the press were not enough: some practical demonstration of ASDIC's power was needed. The best chance for this came during the Spanish Civil War, when ships carrying arms to Republican ports were attacked by 'pirate' (i.e. Italian) submarines. British destroyers came under attack twice, but the Navy very publicly fluffed their chance and didn't manage to sink anything. The First Lord of the Admiralty, Duff Cooper, even had to lie to Parliament, claiming that HMS Basilisk had failed to destroy its target because it turned out that there was nothing there at all; and that furthermore ASDIC wasn't responsible for this false detection either, somebody thought they saw torpedo tracks. Thus the myth of ASDIC's invincibility was preserved. Not that the German navy quite bought this, but it did undervalue submarine warfare (as opposed to surface raiding), and Maiolo concludes that the 'German expectation of Britain's anti-submarine defences matched the false image cultivated by the Admiralty long before the outbreak of World War II' (71).
Maiolo also talks about press scares about the submarine menace. In April-May 1935,
[...] Hector C. Bywater, the naval correspondent for The Daily Telegraph, revealed 'German naval secrets' to his readers, which included sinister plans for a new generation of advanced U-boats. Imaginations imprinted with U-boat crisis of 1917 were confronted with sensational newspaper headlines that read 'Germany's New Submarines - Experiment in Mass Production -- Avoiding Wartime Failure' [...] Bywater and other journalists continued to write sensational stories about Nazi Germany's new generation of lethal U-boats. In September 1936, for instance, under the headline 'How Science May Reinforce a Sinister Weapon', Bywater described how German engineers, 'after years of research and experiment', had foiled contemporary anti-submarine defences by developing a single-plant 'which is said to drive a submarine with equal facility on the surface and on the water'. In late 1936, the Morning Post plastered London with three feet by two feet press headline posters that read 'New German Submarines Designed for Commerce Destruction - Powerful Hydrophones for Locating Shipping'. (61)
The need to allay such fears about submarines was another reason for the exaggerated statements about the effectiveness of ASDIC.
All of this has both parallels with and divergences from the air defence situation. Take some of the parallels first. The most obvious, and least important, one is that ASDIC and RDF (sonar and radar) are physically analogous systems, working on the same principle of active detection via reflected waves (the one via sound, the other via radio). Both presented highly technological challenges to British scientists and engineers and both were kept secret while under development. (RDF was not revealed to the public until 1941.) More interestingly -- at least for me -- press scare campaigns about both submarines and bombers, and what they might do to civilians, increased public interest and participation in otherwise rarefied debates about defence. As part of this process, the war in Spain was crucial in dramatising the threats from both the sea and from the air, and also in providing information about the effectiveness of possible defences against them. But so too was the experience of the First World War in proving the reality of the threats in the first place, with 1917 being a key year in both cases (due to the unrestricted U-boat campaign and the Gotha raids).
As to the differences, thanks to physics ASDIC and RDF were used very differently. Sound attenuates very rapidly under water and so could only be used to detect very nearby submarines. Thus ASDIC was more like AI than CH. So too, ships move much more slowly than aeroplanes and so only local forces could be used to counterattack: so no anti-submarine equivalent of Fighter Command. As for the press scares, without neglecting the efforts of Bywater et al. I think these were an order of magnitude less intense for submarines than for bombers. There just wasn't the same level of concern -- which of course was my original point (though I was interested to find that there was some concern). The question then is (still) why?
One possibility is that the Admiralty's strategy of dropping hints about ASDIC in Parliament and in the press was quite effective. Certainly I'm not aware of anything similar from the Air Ministry and RDF. This may be because it was developed about fifteen years later than ASDIC -- the mid-1930s, becoming operational in 1939 -- at a time when the foreign situation was already darkening: there just wasn't the time to leisurely leak reassuring news about how well-protected Britain was from the air. Another reason may have been that bragging about air defence would undermine the Air Ministry's arguments for a large bomber force ('the only defence is in offence'). The Admiralty likewise wanted battleships rather than destroyers, but there was no way to make battleships into a defence against destroyers.
Another possibility is the immediacy of bombing, as compared with the slow strangulation of blockade. Aeroplanes were a direct threat to civilians, submarines only an indirect one. In terms of making the flesh of newspaper readers creep, there was no contest. Similarly, even though the U-boats in 1917 were far more dangerous to Britain than the Gothas, they didn't actually kill any civilians (aside from merchant seamen). Conversely, the relatively large-scale nature of submarine warfare (relatively continuous attacks, many ships sunks) in the First World War meant that the effectiveness of countermeasures, especially convoying, could be fairly accurately gauged (ie by the rise or fall in tonnage sunk), whereas bombing was on a small scale (days or weeks between raids, damage more dependent on chance) and misinterpretation far more likely: the difference between large-number and small-number statistics.
Ultimately, the relative lack of fear of the submarine is still a bit of a puzzle to me. But that there was more fear than I had realised but that also more official effort was put into assuaging those fears does make it less mysterious.
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