Combatants in the full sense are the regularly authorized military and naval forces of the states. They are liable to the risks and entitled to the immunities of warfare, and if captured become prisoners of war.
(a) The status of combatants is also allowed to two classes which engage in defensive hostilities:—
(1) The officers and crew of a merchant vessel which defends itself by force are liable to capture as prisoners of war.
(2) With regard to levies en masse much difference of opinion exists. Article 10 of the Declaration of Brussels, 1874, was adopted at the Hague Conference in 1899, and may be considered as representing a generally accepted position, namely, "The population of a non-occupied territory, who, on the approach of the enemy, of their own accord take up arms to resist the invading troops, without having had time to organize themselves in conformity with Article 9 [providing for responsible leader, uniform, etc.], shall be considered as belligerents, if they respect the laws and customs of war."[304]
(b) The status of combatants is not allowable for those who, without state authorization, engage in aggressive hostilities.
(1) When in the time of war the officers and crew of a merchant vessel attack another merchant vessel, they are liable to punishment according to the nature of their acts, and the state to which they owe allegiance is only indirectly responsible, nor can they claim its protection.
(2) When bands of men without state authorization and control, such as guerrilla troops or private persons, engage in offensive hostilities, they are liable to the same treatment as above mentioned.
(3) Spies are those who, acting secretly or under false pretenses, collect or seek to collect information in the districts occupied by the enemy, with the intention of communicating it to the opposing force.[305] Such agents are not forbidden, but are liable to such treatment as the laws of the capturing army may prescribe. This may be death by hanging. The office of spy is not necessarily dishonorable.
[§ 101. Non-combatants]
Non-combatants include those who do not participate in the hostilities. In practice this status is generally conceded to women, children, clergy, scientists, artists, professional men, laborers, etc., who make no resistance, whether subjects of the state or not. These are, of course, liable to the hardships consequent upon war.