What is permissible includes every means of war without which the object of the war cannot be obtained; what is reprehensible on the other hand includes every act of violence and destruction which is not demanded by the object of war.
It follows from these universally valid principles that wide limits are set to the subjective freedom and arbitrary judgment of the Commanding Officer; the precepts of civilization, freedom and honor, the traditions prevalent in the army, and the general usages of war, will have to guide his decisions.
A.—MEANS OF WAR DEPENDING ON FORCE
The most important instruments of war in the possession of the enemy are his army, and his military positions; to make an end of them is the first object of war. This can happen:
1. By the annihilation, slaughter, or wounding of the individual combatants.
2. By making prisoners of the same.
3. By siege and bombardment.
1. Annihilation, slaughter, and wounding of the hostile combatants
How to make an end of the Enemy.
In the matter of making an end of the enemy’s forces by violence it is an incontestable and self-evident rule that the right of killing and annihilation in regard to the hostile combatants is inherent in the war power and its organs, that all means which modern inventions afford, including the fullest, most dangerous, and most massive means of destruction, may be utilized; these last, just because they attain the object of war as quickly as possible, are on that account to be regarded as indispensable and, when closely considered, the most human.
The Rules of the Game.