God is only one aspect of the wider subject of moral combat, which means not only what people fought for but how they fought. There are many ways in which one could write about morality and warfare, the most traditional, in Christian (or Islamic) culture at any rate, being concerned with just war or issues of proportionality. The idea that war deranges human morals is also venerable. In the Georgics, Virgil wrote in 29 BC: "Here, right and wrong are reversed; so many wars in the world, so many faces of evil." We know that too, albeit in the language of newspapers or psychology rather than epic poetry. In 1946, around 12 million GIs came home, causing a Stateside moral panic. Papers ran such headlines as "Veteran Beheads Wife with Jungle Machete" or even ‘Veteran Kicks Aunt", while stories about a civilian triple axe murderer were buried inside on page 17. A study highlighted several paradoxes: "Veterans had lost their moral sense in battle, yet they returned home highly critical of the nation's peccadilloes." "Veterans were physical and mental wrecks, yet they threatened to set up a reign of terror through cunning and brawn." "Veterans were returning ‘vicious and godless', even though there had been ‘no atheists in foxholes'." 

Were one so minded, it would be possible to write a moral history of the Second World War in terms of increased divorce rates (in the US and Britain they doubled), illegitimate births, a rising incidence of crime and delinquency attributable to absent authority, or, in the German case, the two million illegal abortions resulting from women — a term one uses liberally — being raped by Red Army soldiers.

The insistent fact which requires explanation is why more civilians than armed combatants were killed in the Second World War than in any previous conflict — 34 million civilians to 21 million forces personnel, if you regard 55 million deaths as an approximate global total. By contrast, in the Great War there were 10.5 million military casualties, but only 100,000 civilian deaths attributable to military action, with a further 4.5 million victims of starvation and disease.

The concept of total war erased a simple distinction between combatants and civilians, as did the dependencies between modern warfare and modern industrial production. The ways in which all countries advertised the total mobilisation of the civilian population was akin to pinning a target disc on them. "The worker attached to a war industry must be considered to be like a soldier who, in the face of the enemy, has the requirement and obligation to remain at his proper combat post," announced the Italian war production commissariat in 1940. These were what British or US air war strategists called the "vital centres", without which men in the field would have no uniforms, guns and ammunition. Ironically, it was all too vivid memories of the mass slaughter in the trenches which heightened the attractions of delivering a knock-out blow, whether through mobile Blitzkrieg in the German case, or saturation bombing in the Allied one, for one of the abiding memories of the RAF's Arthur Harris was of flying over scenes of carnage at Passchendaele as a young pilot. 

Ideology and science contributed to the belief that modern wars involved fundamentally antagonistic systems, which would fight for their survival in ways that resembled the implacability of natural organisms. This was not just Hitler's view, but rather something shared by those who planned future conflicts. "War," a German military planner wrote in the 1920s, was "no longer a clash of armies, but a struggle for the existence of the peoples involved." War was not about nations manoeuvring armies for advantage on tightly circumscribed battlefields but a fight to the death to preserve civilisation, democracy, the Bolshevik revolution, the "master race" or in the Japanese case, the ancient values which made Japanese society unique.