§ 254. Since International Law is a law between States only and exclusively, no rules of International Law can exist which prohibit private individuals from taking up arms and committing hostilities against the enemy. But private individuals committing such acts do not enjoy the privileges of members of armed forces, and the enemy has according to a customary rule of International Law the right to consider and punish such individuals as war criminals. Hostilities in arms committed by private individuals are not war crimes because they really are violations of recognised rules regarding warfare, but because the enemy has the right to consider and punish them as acts of illegitimate warfare. The conflict between praiseworthy patriotism on the part of such individuals and the safety of the enemy troops does not allow of any solution. It would be unreasonable for International Law to impose upon belligerents the duty to forbid the taking up of arms by their private subjects, because such action may occasionally be of the greatest value to a belligerent, especially for the purpose of freeing a country from the enemy who has militarily occupied it. Nevertheless the safety of his troops compels the enemy to consider and punish such hostilities as acts of illegitimate warfare, and International Law gives him a right to do so. It is usual to make a distinction between hostilities in arms on the part of private individuals against an invading or retiring enemy on the one hand, and, on the other, hostilities in arms committed on the part of the inhabitants against an enemy occupying a conquered territory. In the latter case one speaks of war rebellion, whether inhabitants take up arms singly or rise in a so-called levy _en masse_. Articles 1 and 2 of the Hague Regulations make the greatest possible concessions regarding hostilities committed by irregulars.[482] Beyond the limits of these concessions belligerents will never be able to go without the greatest danger to their troops. [Footnote 482: See above, §§ 80 and 81.] It must be particularly noted that merchantmen of belligerents, which attack enemy vessels without previously having been attacked by them, commit a war crime,[483] and that the captains, officers, and members of the crews may, therefore, be punished as war criminals to the same extent as private individuals who commit hostilities in land warfare. [Footnote 483: See above, §§ 85 and 181.] [Sidenote: Espionage and War Treason.]