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.
[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.
[483] See above, §§ [85] and [181].
Espionage and War Treason.
§ 255. Article 24 of the Hague Regulations now enacts the old customary rule that a belligerent has a right to employ all methods necessary to obtain information, and these methods include espionage and treason. But this right stands face to face with the right to consider and punish as war criminals enemy individuals, whether soldiers or not, committing acts of espionage or treason. There is an irreconcilable conflict between the necessity of obtaining information on the one hand, and self-preservation on the other; and accordingly espionage and treason, as has been explained above in § [159], bear a twofold character. On the one hand, International Law gives a right to belligerents to make use of espionage and treason. On the other hand, the same law gives a right to belligerents to consider espionage and treason, committed by enemy soldiers or enemy private individuals within their lines, as acts of illegitimate warfare, and consequently punishable.
Espionage has already been treated above in §§ [159]-161. War treason may be committed in different ways. The following are the chief cases of war treason that may occur:—
(1) Information of any kind given to the enemy.
(2) Voluntary supply of money, provisions, ammunition, horses, clothing, and the like, to the enemy.
(3) Any voluntary assistance to military operations of the enemy, be it by serving as guide in the country, by opening the door of a defended habitation, by repairing a destroyed bridge, or otherwise.