As I write this article I have before me my grandfather's Victory Medal from the First World War. It has inscribed on the reverse side, ‘The Great War for Civilisation 1914-1919'. The absolute certainty of such a justification for Britain's entry into the war seems somewhat hollow as we approach the centenary of the conflict and is a reminder of the shifting sands on which the judgement of history rests.

In the immediate aftermath of the Armistice in 1918 the question of war origins never fully escaped the issue of responsibility...