However, as theorists like the influential Giulio Douhet pointed out, Britain did not rule the air as she did the sea. Not only that, but air power was fundamentally different from sea power: aeroplanes were not limited in scope or direction of movement, and now even the heart of the British Empire itself was vulnerable. London, ‘the great metropolis until now rejoicing in her inviolability’, could be attacked just as easily as anywhere else. ¹⁴

That fact was not lost on the population of London, which still remembered the panic caused by the 1917 Gotha attacks. During the 1920s and 1930s a succession of lurid novels appeared in which the bombing of London produced swarms of refugees like ‘human rats’, ¹⁵or where in the post-apocalyptic ruins of the city ‘the people lived on the rats and the rats lived on the people’. ¹⁶Films like the 1936 science-fiction movie Things to Comeshowed how bombing would be used in a global war that would eventually destroy civilization throughout the world. The opinions of the professionals were no more reassuring. In 1923 J. F. C. Fuller warned that the dropping of poison gas on London might injure as many as two hundred thousand people in half an hour, and ‘throw the whole city into panic’. ¹⁷Douhet was even more graphic in his predictions, and claimed that bombing a city like London would result in ‘a complete breakdown of the social structure’, which would inevitably lead the people to rise up in revolution against their own government. ¹⁸

All these various prophets of air power singled out London in their descriptions because at that time the British capital was still by far the most powerful city in Europe, and also the one most protected by natural barriers. If London were vulnerable, how much more vulnerable must every other European city be? As a consequence, fear of bombing was fairly universal throughout western Europe between the wars. Even Canada and the USA were not immune to such anxieties, despite their geographical remoteness from any enemy – as was demonstrated by the faintly absurd air-raid scares in Ottawa and New York during the last year of the war, and again in 1942. ¹⁹But it was only in Britain that such concerns reached virtual hysteria. By the 1930s even the most enthusiastic champion of bombing, J. M. Spaight, was forced to admit to a widespread pessimism among his contemporaries, who foresaw ‘a fate comparable to that of Sodom and Gomorrah’ for British cities. ²⁰

As the Second World War approached, the predictions became more and more gloomy. In 1937, the military theorist Sir Malcolm Campbell wrote the following account of the likely outcome of an air raid on London:

First would come hundreds of aeroplanes… each carrying up to a thousand small incendiary bombs. These would be dropped at a rate of one every five seconds, and each machine would leave a string of fires in its wake. If all the fire-fighting appliances in the country were concentrated in the one place, they would not be able to cope with a tenth of the fires that would rage over the whole area attacked. Even if they could, hard on the heels of the fire-raisers would follow fleets of heavy bombing machines, dropping their loads of high-explosive bombs on a city already virtually fated to destruction by fire. And as if that were not enough, then would come other fleets of aircraft to drench the flaming ruins with poison gases. Unless the people could take refuge in safety below ground, the casualties in a city like London must amount to a million or even more, while the material damage would be simply incalculable. The picture is not over-drawn – it is what inevitably will happen to a country which fails to take the elementary precaution of making itself strong enough to hold what it has. ²¹

When such a premonition is extended beyond just one city to ten, twenty, fifty cities, it is no longer a vision of Sodom and Gomorrah. It is a vision of Armageddon.

It must be stressed at this point that not everybody believed that such destruction was inevitable. There had been many and varied attempts to ban bombing ever since the first Hague Peace Conference in 1899 but, as is so often the case with such conferences, the proposals were always rejected by too many of the countries that really mattered. ²²

In one famous instance, in March 1933, the peace conference at the League of Nations took up the question of firebombing. Poison gas had already been banned in 1926 because its uncontrollable nature threatened the lives of innocent civilians; it was argued now that fires caused by incendiaries were every bit as uncontrollable as gas when dropped on city targets, so should also be banned. Everyone agreed, and for a while it looked as though firebombing would indeed be banned. The conference was already working out the practical details when, in October that year, the newly elected Adolf Hitler walked out and withdrew from the League of Nations. Without Germany, the ban meant nothing. Ironically, Hitler’s action had ensured the death of hundreds of thousands of his own countrymen. ²³

* * *

Over the next few years the whole world rearmed itself, and rapidly sank back into the quicksand of war. It is difficult now, even with hindsight, to see how another world war could have been avoided after the Nazis took power in Germany. Repeated attempts to mollify Hitler at the negotiating table proved a waste of time: the entire doctrine of the Nazi Party was centred on preparing for war. ²⁴By 1937 the newly formed Luftwaffe was rehearsing its tactics with the bombing of republican towns like Guernica in the Spanish Civil War. In the spring of 1938 Hitler annexed Austria. In 1939, despite frantic British attempts at appeasement, he marched into Czechoslovakia. In September he invaded Poland, followed by Denmark, Norway, Holland, Belgium and France. In just under ten months Hitler and his allies had taken control of virtually the whole of mainland Europe.

Despite all the dire predictions of the 1930s, the war in the air was fairly restrained until this point. At the outbreak of hostilities President Roosevelt had appealed to both sides to renounce the ‘bombardment from the air of civilian populations and unfortified cities’, and both sides had hastened to agree. ²⁵Neither wished to provoke the ire of the world’s greatest industrial nation.

The British in particular promised that they would ‘never resort to the deliberate attack on women and children and other civilians for purposes of mere terrorism’, ²⁶and for a long time they kept their promise. During the six-month lull between the invasions of Poland and Norway, the RAF took serious losses in coastal raids on the German Navy: these were completely unsuccessful because they were forbidden to attack ships when they were at their most vulnerable – in port – because of the possibility of hitting civilians. During the battle for Norway air crew were instructed not to use any bombs, just their machine-guns to avoid hitting innocent bystanders. ²⁷For all Britain’s refusal to ratify international agreements on bombing, she began the war with admirable, if somewhat unrealistic, restraint.

With the exception of the bombing of Warsaw in 1939, Germany exercised similar control. It made no sense to destroy the cities and industries of the countries she wanted to occupy, and Hitler had no intention of provoking America into renouncing its neutrality. In any case the Luftwaffe was overwhelmingly a tacticalair force – it confined its activities mostly to the battle zone, by dive-bombing and strafing opposing troops. The strategicbombing they carried out was generally directed at the destruction of enemy airfields and transport links, not civilian populations.