Autre temps, autre moeurs. These wars were fought with conscript armies. Ditto for Vietnam, with similar effect (fragging). The ruling classes have learned their lessons since then, and started relying on mercenary forces. As the neo-classical wisdom on specialization teaches us, it is more effective to lure the lumpenproletariat to mercenary service in the imperial army, and to fleece the working class to foot the bill, instead of forcing the latter to do the fighting.
BTW, who said that he can hire a half of the working class to kill the other half? Judging from the experience of the US mercenary forces, it takes much less than a half.
Wojtek