In accordance with the principles underlying the first and second of these resolutions, The Hague Convention, No. iii. of 1907 (ratified generally by Great Britain on November 27, 1909), has now laid down as a principle of International Law, binding upon the contracting Powers, that—
(1) "Hostilities between them ought not to commence without a warning previously given and unequivocal, in the form either of a reasoned declaration of war, or of an ultimatum, with a conditional declaration of war."
And the Convention goes on to provide that—
(2) "The state of war ought to be notified without delay to neutral Powers, and shall be of no effect with reference to them, until after a notification, which may be made even telegraphically. Nevertheless, neutral Powers may not plead absence of notification, if it has been shown beyond question that they were in fact cognisant of the state of war." Any reference to the need of an interval between declaration and the first act of hostility (such as is contained in the third of the resolutions of the Institut) was deliberately omitted from the Convention, although a declaration immediately followed by an attack would obviously be of little service to the party attacked. (See the present writer's Laws of War on Land (written and unwritten), 1908, P. 18.)
SECTION 2
The Immediate Effects of the Outbreak of War
Enemy Residents
Before any actual hostilities have taken place, each belligerent acquires, ipso facto, certain new rights over persons and property belonging to the other, which happen to be at the time within its power,[045] e.g. the right, much softened in modern practice, and specifically dealt with in The Hague Convention, No. vi. of 1907, of capturing enemy merchant vessels so situated.
The following letter deals with the permissible treatment of enemy persons so situated; and was suggested by a question asked in the House of Commons on February 25, 1909, by Mr. Arnold-Forster: viz. "What would be the status of officers and men of the regular Army of a hostile belligerent Power, found within the limits of the United Kingdom after an act or declaration of war; and would such persons be liable to be treated as prisoners of war, or would they be despatched under the protection of the Government to join the forces of the enemy?" The general effect of the Attorney-General's reply may be gathered from the quotations from it made in the letter.