Aerial bombing to destroy cities was the most notable development in warfare in the 20th century, and its legacy lives to this day. The debate about its utility and morality, fuelled by wars against Iraq and in the Balkans, pours forth endlessly from newspaper pulpits. "Shock and awe" is a recent formulation, but the notions of drama and surprise, as well as novelty and danger, have long been a central part of the preoccupation with bombing from the sky, outweighing even humanitarian concern with the fate of individuals. Writers of imaginative fiction, as Sven Lindqvist revealed in his History of Bombing (Granta, 2001), were far in advance of the scientists who made these war crimes possible, dreaming up improbable scenarios that became reality.

Apart from the catastrophes inflicted on Hiroshima and Nagasaki, two other towns, Guernica and Dresden, have become embedded in popular memory as exemplars of something particularly new and dreadful. Each became encrusted with its own particular legend. The bombing of Guernica by the Nazis in 1937 was once presented as the first unprovoked attack on an undefended town, although we are now reminded that such attacks had occurred many times over the previous 20 years, notably in Iraq, India and Morocco. Guernica became famous only because it was in Europe, and the attack was observed by journalists.

Dresden, bombed by the RAF in February 1945, three months before the end of the Second World War, was perceived at the time, and has been ever since, as an Allied war crime, an especially dreadful episode in the history of aerial bombing. Yet the intensity of the attacks, the lack of warning, the horror of the firestorm, and the thousands of casualties, had all been phenomena associated with the destruction of other cities. The fate of Dresden was singled out for criticism partly because it struck a chord in influential sections of Britain's Europe-loving intelligentsia, those who had visited its cultural monuments or lived and studied there. It is now usually remembered as a moral stain on the reputation of the Allies, uncomfortably justified as some kind of terrible bureaucratic mistake, the fruit of a policy that should have been wound up months earlier.

Winston Churchill admitted that the bombing had been authorised "under other pretexts" than terror, and much of the revisionist work done in the past 60 years to try to save the reputation of Bomber Command and Arthur Harris, its energetic and ruthless chief, has stressed the importance of these "other pretexts". Dresden was not just one of Europe's loveliest cities, famed for its porcelain shepherdesses (even though they really came from untouched Meissen next door), it was an important relocation point for many of Germany's war-related industries, and a significant transit centre for the war on the eastern front (only a few miles away, in February 1945). The city, in this version of history, was a justifiable military target.

Frederick Taylor is the latest of these revisionists, and in his book Dresden, he accumulates a solid dossier of sometimes rather indigestible facts, culled from the archives and interviews with survivors, to justify the bombing. It is a clumsy and overwritten book, produced with an American audience in mind, and with an inbuilt confusion between the contemporary record and what people have recalled with hindsight. Yet in spite of the muddle, the story was well worth retelling. Taylor revisits the familiar arguments about the relocation of industries and the importance of communications, and adds one of his own. Far from being a product of the Enlightenment, as its splendid architecture might suggest, Dresden was a pretty nasty place. It had always been horrid to its Jewish population, burning down their synagogues and shipping them off to Auschwitz during the war. Some of them were even saved by the bombing of the city, and were able to rejoice.

These arguments are interesting in themselves, and go some way to demystifying the Dresden legend by making the point that the town was not so very different from the other German targets of Bomber Command. Yet they do not address the policy of strategic bombing itself, or the question of its justification. Throughout the war, there was a battle between newspapers that voiced what they believed to be the public's demand for vengeance, in return for the bombing of British cities by the Nazis, and a determined minority of politicians and churchmen who believed that the destruction of German cities was politically and militarily ineffective - and morally obnoxious.

The debate has stretched from that date to this, with renewed currency as some Americans seek indiscriminate vengeance for the twin towers atrocity while others look for a more sophisticated response. What even Taylor is obliged to admit is that Dresden came at a critical moment in the wartime debate, when the moral arguments of the opponents of strategic bombing briefly won through. When Churchill called for a review, Taylor suggests, he was already conscious of a change in the public mood. Possibly "he sensed that, far from being war-weary and vengeful, the British people had become - though still eager to see an end to the war - concerned about the things that were being done in their name to gain the final victory". Dresden symbolised that change of heart.

Dresden was also perceived not just as a moral mistake but as a public relations disaster. The Americans were more sensitive to such matters. A few weeks after the bombing, Henry Stimson, Roosevelt's secretary of war, asked to see the list of Japanese cities being considered as targets for the first use of the atomic bomb. Top of the list was Kyoto, an industrial city, but also a legendary centre of Japanese history and culture. "I don't want Kyoto bombed," said Stimson. Dresden preserved Kyoto, but it did not save Hiroshima and Nagasaki.

Richard Gott's new history of Cuba will be published this autumn by Yale University Press