Murray Rothbard on modern war vs. pre-modern war

It was not always thus.  During the Middle Ages, the scope of wars was far more limited.  Before the rise of modern weapons, armaments were so limited that governments could – and often did – strictly confine their violence to the armies of the rival governments.  It is true that tax coercion increased, but at least there was no mass murder of the innocents.  Not only was firepower low enough to confine violence to the armies of the contending sides, but in the pre-modern era there was no central nation-state that spoke inevitably in the name of all inhabitants of a given land area.  If one set of kings or barons fought another, it was not felt that everyone in the area must be a dedicated partisan.  Moreover, instead of mass conscript armies enslaved to their respective rulers, armies were small bands of hired mercenaries.  Often, a favorite sport for the populace was to observe a battle from the safety of the town ramparts, and war was regarded as something of a sporting match.  But with the rise of the centralizing State and of modern weapons of mass destruction, the slaughter of civilians, as well as conscript armies, have become a vital part of inter-State warfare. 

Suppose that despite possible libertarian opposition, war has broken out.  Clearly, the libertarian position should be that, so long as the war continues, the scope of assault upon innocent civilians must be diminished as much as possible.  Old-fashioned international law had two excellent devices to accomplish this goal: the “laws of war,” and the “laws of neutrality” or “neutral’s rights”…  In short, the libertarian tries to induce the warring States to observe fully the rights of neutral citizens.  The “laws of war,” for their part, were designed to limit as much as possible the invasion by warring States of the rights of civilians in their respective countries.  As the British jurist F.J.P. Veale put it: 

The fundamental principle of this code was that hostilities between civilized peoples must be limited to the armed forces…  It drew a distinction between combatants and non-combatants by laying down that the sole business of the combatants is to fight each other and, consequently, that non-combatants must be excluded from the scope of military operations.

In the modified form of prohibiting the bombardment of all cities not in the front line, this rule held in Western European wars in recent centuries until Britain launched the strategic bombing of civilians in World War II. Now, of course, the entire concept is scarcely remembered, since the very nature of modern nuclear warfare rests upon the annihilation of civilians.

~ Murray Rothbard, For a New Liberty, "War and Foreign Policy," pp. 332-334

1973