for is seen as unremarkable; only after the crossings of the Meuse, the sudden success of the break-out and the insubordination of Guderian and other tank commanders during the rush down the Somme valley, would "Blitzkrieg" have been adopted as an explicit theory, in this view making Operation Barbarossa the first and only Blitzkrieg campaign. Guderian presented the situation in his postwar book Erinnerungen eines Soldaten (Memories of a Soldier 1950, published in English as Panzer Leader) according to the second hypothesis, posing as a lone voice against the reactionary German officer corps. In 2006, Adam Tooze wrote that the quick victory in France was not the consequence of a logical strategic synthesis but a "risky improvisation" to cope with strategic dilemmas that Hitler and the German military leaders had been unable to overcome before February 1940. Tooze wrote that the Allies and the Germans had no interest in acknowledging the importance of improvisation and chance in the sensational victory of 1940. The fabrication of a Blitzkrieg Myth was convenient for the Allies to hide the incompetence that had led to their defeat. Rather than resort to technological determinism, German propaganda emphasised the machinery of the German army and that of the Allies, juxtaposing it with the heroic individualism of German soldiers, notably in the film Sieg im Westen (1941). OKW explained the victory as a consequence of the "...revolutionary dynamic of the Third Reich and its National socialist leadership". Tooze wrote that a debunking of the technological interpretation of the German victory should not lead to the conclusion that it was the genius of Manstein or the superiority of German soldiers that caused the victory. There was no German grand-strategic synthesis; the course of the 1940 campaign depended on the economic mobilisation of 1939 and the geography of western Europe. During the winter of 1939–1940, the quality of German armoured forces was substantially improved. The plan attributed to Manstein was not a revolutionary departure from traditional military thinking but the concentration of superior force at the decisive point, a synthesis of "materialism and military art". The German army committed all its armoured units to the offensive and had it failed, would have had none left to resist an Allied counter-offensive. Casualties were high but the swift end to the campaign made them bearable. The was also fully committed but the Allied air forces held back a substantial reserve, in