In offensive war, the government must do just this. It must wage war against its people's virtue before it wages war against its declared enemy. Self-interest remains a motive to the combatant, but it is now the government, and not an invader, which threatens his life and liberty if he fails to fight. All wars generate a certain devotion to military unit, but habitual aggressors tend to elevate this above the natural affection toward friend and family. The love of country is replaced by love of empire.
More perversions follow.
Since the enemies are not invaders, they cannot stop the conflict simply by returning home. They must be dehumanized, so that they may be killed more easily. All at the expense of the god-fearing taxpayer. See also Jeff Elkin's article on this process. Invaders seldom bring their women and babies along to be raped and impaled.