It is against the usage of modern war, because it is savage, to resolve, in hatred and revenge, to give no quarter.
All troops of the enemy, known or discovered to give no quarter to any portion of the army, receive none.
§ 36. The Law of Nations allows every sovereign government to make war upon another sovereign state, and, therefore, admits of no different rules regarding the treatment of prisoners of war, although they may belong to the army of a government which the captor may consider as a wanton and unjust assailant; nor has the defensive government the right to proclaim that it will ill-treat the prisoners it may make, against the rules and laws of regular warfare.
§ 37. Modern wars are not internecine wars, in which the killing of the enemy is the object. The destruction of the enemy, in modern war, and, indeed, modern war itself, are means to obtain that object of the belligerent which lies beyond the war.
Unnecessary or revengeful destruction of life, is not lawful.
Outposts, sentinels, or pickets, are not fired upon, except to drive them in, or when a positive order, special or general, has been issued to that effect.
The use of poison in any manner, be it to poison wells, or food, or arms, is wholly excluded from modern warfare. He that uses it, puts himself out of the pale of the law and usages of war. Thousands of years ago it was held that no one who fears a supreme avenger of wrong, will poison his arrow.
§ 38. Whoever intentionally inflicts additional wounds on an enemy already disabled from fighting, or kills such an enemy, or who orders or encourages soldiers to do so, shall suffer death if duly convicted, whether he belongs to the army of the United States, or is an enemy captured after having committed his misdeed.
§ 39. Arms, ammunition, horses, wagons, and implements of war, as well as provision and clothing, taken on the battle-field, or captured otherwise, belong to the United States.
All regulation arms found upon prisoners of war belong to the United States; but small arms, not usually belonging to the regulation arms of the respective troops, such as daggers or private pistols, belong to the captor or captors.