Historically the end has justified the means in warfare.

But as regards the towns of those peoples which Yahweh your God gives you as your own inheritance, you must not spare the life of any living thing.

Deuteronomy 20:16

But I tell you, love your enemies...

Matthew 5:44

Might has made right; victors have set the standards of legitimacy. Even in the Second World War, the Allies were able to set standards at Nuremberg only because they were victorious. And in the light of the wholesale slaughter of civilians at Nagasaki, Hiroshima and Dresden, there is some question whether Allied criteria for crimes against humanity represented a double standard.

Military legitimacy relates to the balance between might and right. Its standards are concerned primarily with protecting civilians and other non-combatants from the ravages of war. Standards of military legitimacy evolved from the Just War tradition and are incorporated in the law of war. But the Judeo-Christian tradition began with holy war, where no distinction is made between combatants and non-combatants, only between good and evil. Its brutal progeny can be seen in contemporary primal violence in the Middle East, Northern Ireland and Bosnia.

The concept of chivalry evolved from the Middle Ages to provide a moral foundation for the protection of civilians in war. A variety of chivalry survived in the antebellum South until it became a cultural casualty of the War Between the States - a war that introduced the theory of collective responsibility to justify total war. In the nineteenth century the US would demonstrate its proficiency in total war, but later learn the painful lessons of limited war.