4. Prisoners of war should be neither killed nor reduced to slavery, but simply prevented from doing mischief. As to the means employed to deprive an enemy of his life, humanity, with just reason, interdicts the use of certain cowardly and perfidious means; as, for instance, poisoned bullets, or too cruel means of destruction, or lastly, assassination. Thus, it would be odious to send traitors secretly charged to kill the hostile general. There is, besides, no example of such attempts in modern wars, and the human conscience would unanimously reprove them. Thus much concerning the rights war gives over the lives of enemies. Let us consider now the duties regarding property. 1. War gives the right to destroy the property of the enemy; it is what is called the _right of ravage_. But ravage should not be pursued for its own sake, but only to weaken the enemy. Thus we should as much as possible spare public monuments, works of art, etc. 2. It is a right of war to acquire and appropriate things belonging to the enemy until agreement as to the moneys due, including the expenses of the war. 3. It is by virtue of these principles that, in case of naval encounters, it is justifiable to take possession of the enemy's vessels, and not only of men-of-war, but of merchant-men and the goods they carry. 4. This right upon the enemy's property is only the sovereign's; he alone has a right to appropriate, in the name of the State, the property of the invaded territory, by way of restitution or guaranty; but war does not confer upon single individuals the right of taking possession of people's property and appropriating it: this is simply pillage. =118. Conquest.=--We call _right of conquest_ the right which belongs to a State to bring under its sovereignty the whole or part of another State, by virtue of the right of war. Conquest, it will be seen, is but the right of the strongest. It is contrary to the principle of modern political societies, which requires that the State rest on the free contract of citizens, and that a people should only be subject to laws consented to. It is not easy to have an official authentication of this consent; but it is certain that there are annexations that are voluntary, and others that are not. The latter, it must be hoped, will become less and less frequent as the idea of justice among nations develops. =119. Neutrality.=--We call _neutrality_ the situation of States which, in a case of war, side with neither the one nor the other of the belligerents, but remain at peace with the two parties. They are, therefore, obliged to practice toward them the laws of natural right impartially: if, for example, they render to one a service of humanity, they must not refuse the same service to the other. They must not furnish means of hostility to either the one or the other, or they must furnish them to both. They must lend their good offices for a settlement if they have any chance of being listened to.