This is an examination of the costs of the First World War, considering the direct political, material and human consequences and shows how the Great War left an indelible imprint on the cultural life of the West, drawing on chronologies, biographies and maps. The gigantic scale of the military effort during these four excruciating years was phenomenal - 70 million men were mobilized into uniform and of those about nine million died. The effect of this upheaval on politicians, generals, soldiers and civilians is followed through four separate phases of the war: the war of illusions of 1914; the war of stalemate and stagnation of 1915; the war of the great slaughter of 1916-17; anad the re-emergence of social conflict and revolution in 1917-18, which precipitated the Armistice on 11 November 1918.