"… whereas in the ancient regime, the sovereign manifested his power over life through exercising his right to kill, now in the modern regime the focus is upon the “right of the social body to ensure, maintain, or develop its life. Yet wars were never as bloody as they have been since the nineteenth century, and […], never before did regimes visit such holocausts on their own populations.”
With these descriptions, Foucault emphasizes the dangerous side of productive power… .
A new “power of death” expressed in the bloody wars, genocides, and holocausts of modernity
"… now presents itself as the counterpart of a power that exerts a positive influence on life, that endeavors to administer, optimize, and multiply it, subjecting it to precise controls and comprehensive regulations. Wars are no longer waged in the name of a sovereign who must be defended; they are waged on behalf of the existence of everyone; entire populations are mobilized for the purpose of wholesale slaughter in the name of life necessity: massacres have become vital. It is as managers of life and survival, of bodies and the race, that so many regimes have been able to wage so many wars, causing so many men to be killed."
Having highlighted the death and life dialectic of the modern power configuration, Foucault discusses how mere survival rather than living well (eu zein) motivates modern war initiatives as well as their terminations. As he explains,
"… the power to expose a whole population to death is the underside of the power to guarantee an individual’s continued existence. The principle underlying the tactics of battle—that one has to be capable of killing in order to go on living—has become the principle that defines the strategy of states. But the existence in question is no longer the juridical existence of sovereignty; at stake is the biological existence of a population. If genocide is indeed the dream of modern powers, this is not because of a recent return of the ancient right to kill; it is because power is situated and exercised at the level of life, the species, the race, and the large-scale phenomena of population."
- from Per Caritatem