Clausewitz was probably commenting on the use of force between independent states on the battlefield and did not have civil conflicts in mind. Time seems to have proved Clausewitz wrong. The nineteenth century saw the adoption of the first international conventions regulating the conduct of warfare between states, and the twentieth century witnessed the slow genesis of the need for international law to regulate internal armed conflicts. Whilst the trend in conventional international law since 1832 has gone against Clausewitz, his comment is still valid for the actual practice of war in internal armed conflicts throughout the centuries and up to the present day. From the French revolution where General Westerman declared in 1793, ‘Il n'y a plus de Vendée, elle est morte sous notre sabre libre avec ses femmes et ses enfants’, to the genocide in Rwanda in 1994, internal armed conflicts remain inhumane and destructive.

The acceptance of the principle that international law could regulate some aspects of internal armed conflict was a long and slow process. Civil conflicts were generally thought to fall within the reserved domain of each state. The state was free to decide on the means to restore peace and order. Taking up arms against your state was in itself a crime under the law of the state concerned and insurgents were usually tried for treason.