[Cross-posted at Revise and Dissent.]

Five years ago yesterday, like so many others I watched in horror and confusion as the September 11 attacks unfolded on the other side of the planet and on my TV screen. It seemed so novel and so strange, to think of humble airliners being used as weapons. (I still catch myself looking up at the sky when I hear one flying low, and wondering for a second -- 'Is it going to ... ?') But it wasn't really all that novel. Airliners and terror go way back.

However, it wasn't that people were worried that airliners in flight would be seized by terrorists and flown into important buildings. Instead, the fear was that a nation's airliners could be quickly and easily turned into bombers and used en masse to deliver a knock-out blow against an unsuspecting victim. In the 1920s and early 1930s, this idea was very widespread in Britain, at least among those people who were thinking about how to win, or better yet, prevent the next war.

The basic idea was that a bomber and an airliner or air transport are fundamentally similar: they are both big, heavy aircraft designed to carry a large payload over a long distance. In fact, early airliners were often just war-surplus bombers; conversely, some bombers had civilian origins (such as the Handley Page Hyderabad, developed from the H-P W.8). Strap on some external bomb racks, fit a bombsight and maybe a machine gun or two to ward off enemy fighters, and you have a useful military machine. P. R. C. Groves was the first to sound the tocsin, in 1922:

An aeroplane which can carry a certain number of passengers a certain distance at a certain speed is capable of carrying an equivalent weight in bombs for the same distance at the same speed; and any passenger-carrier which is efficient as such can be transformed into an efficient bomber.¹

Groves continued to fill many column-inches of newsprint with his warnings about the danger of civil-military conversion, and he was followed in this by many writers; Liddell Hart was still discussing the possibility in his The Defence of Britain, written in mid-1939. But why was it considered such a problem? Three reasons.

First was the idea that there was little or no defence against bombers, that they could not be stopped, and that the destruction that they would wreak upon a city like London would be catastrophic. The more bombers there were, the more casaulties there would be.

The second reason was that it added a big element of uncertainly into calculations of national airpower. In a matter of days or even hours, an aggressor could add hundreds of bombers to its air force. What was formerly a manageable threat could become an existential one almost overnight.

The final, and most important, reason was Germany. Groves had recently been in involved in the monitoring of German aerial disarmament, as mandated by the Versailles treaty -- it was forbidden from possessing any military aircraft whatsoever. But he believed that the booming German civil aviation industry was in part a front for a covert military program, which was laying the basis for a future air force. German airlines came to dominate central European routes and German aircraft were much in demand overseas. And Britain was falling behind: in 1928, the number of air-miles flown by British airliners was less than a third of those flown by German ones, according to the responsible British minister, Samuel Hoare.² So, even though it had been disarmed in the air in theory, in practice Germany was still a threat.

But when the next war came, neither the Germans nor anybody else added clouds of airliner-bombers to their aerial fleets. Why not? There are several reasons, but the main one was probably capitalism. Airlines have to make a profit, so they like fuel-efficient and cost-effective aircraft. These are secondary considerations for air forces (or at least are judged by different criteria): they want bombers which can get in to a target area and out again as fast as possible. These goals were incompatible: flying fast is not, generally speaking, cost-effective (one reason why Concorde is no more). With the occasional exception (such as the surprisingly fast times of the Douglas DC-2 and the Boeing 247 in the 1934 MacRobertson Air Race), by the late 1930s airliners literally couldn't keep up with military aircraft, and would simply have been target practice for fighter pilots.³

So much for that idea then. But there was one important consequence of this somewhat overdrawn fear. In 1932, the long-awaited Disarmament Conference opened in Geneva. One item on its ambitious agenda was clipping the bomber's wings, and the obvious way to do this was to ban it altogether. The problem was, of course, that even if every country in the world destroyed their bombers, then they might end up at the mercy of an unscrupulous nation with a big civilian air fleet. Various solutions were contemplated, such as placing either military aviation or civil aviation, or both, under some form of international control. But no agreement could be reached (Britain, for one, was too attached to its use of bombers for Imperial 'policing') and so the opportunity was missed. If it had been seized, would it have prevented Guernica, Rotterdam, Dresden -- Hiroshima? Or would it have given expansionist countries a free hand? Would Britons have felt more secure, or less? Would appeasement have ended sooner, or later, or never have happened at all? The shadow of the airliner lies over the past, as it once darkened the future.

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1. The Times, 22 March 1922, p. 14. [↩]
2. There is of course a critique of British aviation and industrial policy at work here; Groves believed that the government should subsidise British civil aviation, just as the Continental countries did. [↩]
3. The Luftwaffe did use Ju 52 transports as bombers in Spain and Poland, but these were not impressed from civilian life. [↩]