By 1918, four years of total war had produced a complete mobilization of scientists, scholars and their institutions throughout Europe, the British Empire, and the United States. Public men spoke freely of the implications of a ‘technological war’ run by engineers and chemists. And in the years following the Armistice, historians were eager to record the achievements of the professions, and the effects of the war on their self-image. Memories of the First World War, as Paul Fussell reminds us, remain and shape the texture of our daily life. The parapet, wire and mud have become permanent features of human existence. In a similar way, the war of 1914–18 had enduring consequences for science and scientists, rarely appreciated until the end of the Second World War. Scholars and savants deserted their classrooms for the trenches, industries and war offices, while professional bodies turned themselves into useful extensions of military departments. By October 1914, the infamous Professors' Manifesto, with its Appeal to the Cultured Peoples of the World had identified German science with German war aims, and the natural sciences were fully at war. Scientific knowledge applied to the war was – at one and the same time – a fulfilment of the Enlightenment project of reason, and a violation of the Enlightenment ethos of humanism and internationalism.