What made these men - and a few women - risk their lonely, lingering deaths? It was not even as if their putsch had any realistic hope of success against the increasingly iron grip of the SS state. Their actions, as Germany crumbled in a war she could not win, were rather the product of a deeper desire to atone for and expiate the crimes of the regime that had made the name of their beloved country stink in the world's nostrils. Some plotters had been planning to assassinate Hitler and overthrow his regime as early as 1938, before he had launched his ruinous war. Time and again, their efforts had been thwarted as if by a malign fate. Repeatedly, as if protected by a providential sixth sense, the dictator had cancelled or rushed through parades at which he was to have been shot down or blown up by young officers acting as the world's first suicide bombers.

The military plotters were spurred to act not only by their revulsion at the cruel horrors that many of them witnessed on the eastern front as the Holocaust got under way, but by their own sense of guilt. In its early days the Nazi regime had made the Army complicit in their crimes - the Wehrmacht had welcomed and even provided the weapons and facilities for the bloody June-July 1934 Night of the Long Knives purge of the SA Brownshirts. Many officers -Stauffenberg included - had seen the Nazis as reliable anti-Bolsheviks, and had cheered on Hitler's rearmament programme, jibbing only when they saw - too late - that he was leading Germany into the abyss of an unwinnable war. It was little wonder that Whitehall regarded the plotters as just a milder version of the Nazis. One Foreign Office mandarin, Sir John Wheeler-Bennett - ironically a later historian of the resistance - even applauded the SS in a notorious memo for saving the Allies later trouble by getting rid of the most talented Germans before the war's end.

By 1944, their overtures ignored by the Allies, and after the failure of their umpteenth assassination plot, the conspirators had lost heart. Fatalistically, as the war turned from Teutonic triumph to what one conspirator, Admiral Wilhelm Canaris, predicted would be Finis Germania, they seemed to accept that, for better or worse, in the words of one of his victims, General Werner von Fritsch, Hitler was "Germany's destiny". And then the situation was transformed by the advent of Stauffenberg. A latecomer to the conspiracy, he was recruited to the plot after suffering horrifying wounds when his staff car was strafed by an Allied aircaft in Tunisia early in 1943. The handsome young officer lost an eye, a hand, and all but three fingers of his remaining hand, but, undaunted, he insisted on remaining in the Wehrmacht and took up a key position as Chief of Staff in the Reserve Army - a sort of Home Guard encompassing all soldiers not at the fighting fronts.