Certain principles became more definite through the decisions in consequence of the Spanish-American War of 1898. As to the number of vessels necessary, the Supreme Court of the United States said, "As we hold that an effective blockade is a blockade so effective as to make it dangerous in fact for vessels to at tempt to enter the blockaded port, it follows that the question of effectiveness is not con trolled by the number of the blockading force. In other words, the position cannot be main tained that one modern cruiser though suffi cient in fact is not sufficient in law.° (The (Mimic Rodriguez, 174 U. S. 510). It was also stated that a captured vessel was not in condi tion to dispute the effectiveness of the force which captured her, and further it was thought *a sufficient compliance with the obligations of international law if the blockade made egress or ingress dangerous in fact.° In the Russo Japanese War, 1904-05, the Japanese regula tions provided that: *Blockade is to close an enemy's port, bay or coast with force, and is effective when the force is strong enough to threaten any vessels that attempt to go in or out of the blockaded port or bay or to approach the coast.° The duration of liability to capture had been subject to difference of opinion. Continental opinion has inclined to the side of liability only when taken in the act or when continu ously pursued. British and American opinion has made liability to begin upon departure on the voyage and to terminate with its comple tion when the intent to violate a blockade is present, and if a vessel has escaped from a blockaded port the liability to capture continues until the vessel reaches her home port. An at tempt was made by the International Naval Conference of 1908-09 to reconcile in the Dec laration of London these and many other dif ferences of opinion upon details of instituting and maintaining a blockade. This naval con ference represented the United States. Ger many, Austria, Spain, France, Great Britain, Italy, Japan, Netherlands and Russia, the pow ers especially concerned with the conduct of naval warfare. The conclusions were declared to correspond in substance to the generally recognized principles of international law.' The articles relating to blockade in the Declaration of London numbered 21 and embody what up to August 1914, when war broke out in Europe, was regarded as a satisfactory statement of the law of blockade. These articles are as follows: 'Article 1. A blockade must be limited to the ports and coasts belonging to or occupied by the enemy.
Art 2. In accordance with the Declaration of Paris of 1856, a blockade, in order to be bind ing, must be effective — that is to say, it must be maintained by a force sufficient really to prevent access to the enemy coast.
Art. 3. The question whether a blockade is effective is a question of fact.
Art. 4. A blockade is not regarded as raised if the blockading forces are temporarily driven off by bad weather.
Art. 5. A blockade must be applied impar tially to the ships of all nations.
Art. 6. The commander of a blockading force may grant to a warship permission to enter, and subsequently to leave, a blockaded port.
Art. 7. In circumstances of distress, acknowl edged by an authority of the blockading forces, a neutral vessel may enter a place under block ade and subsequently leave it, provided that she has neither discharged nor shipped any cargo there.
Art. 8. A blockade, in order to be binding, must be declared in accordance with article 9, and notified in accordance with articles 11 and 16.
Art. 9. A declaration of blockade is made either by the blockading power or by the naval authorities acting in its name.
It specifies (1) The date when the blockade be gins; (2) The geographical limits of the coast blockaded; (3) The delay to be allowed to neu tral vessels for departure.
Art. 10. If the blockading power, or the naval authorities acting in its name, do not establish the blockade in conformity with the provisions which, in accordance with article 9 (1) and (2), must be inserted in the declara tion of blockade, the declaration is void, and a new declaration is necessary in order to make the blockade operative.
Art. 11. A declaration of blockade is noti fied— (1) To the neutral powers, by the blockading power by means of a com munication addressed to the govern ments themselves, or to their represent atives accredited to it.
(2) To the local authorities, by the officer commanding the blockading force. These authorities will, on their part, inform, as soon as possible, the foreign consuls who exercise their functions in the port or on the coast blockaded.
Art. 12. The rules relative to the declara tion and to the notification of blockade are applicable in the case in which the blockade may have been extended or may have been re established after having been raised.
Art. 13. The voluntary raising of a block ade, as also any limitation which may be intro duced, must be notified in the manner pre scribed by article 11.
Art. 14. The liability of a neutral vessel to capture for breach of blockade is contingent on her knowledge, actual or presumptive, of the blockade.
Art. 15. Failing proof to the contrary, knowledge of the blockade is presumed if the vessel left a neutral port subsequently to the notification of the blockade made in sufficient time to the power to which such port belongs.
Art. 16. If a vessel which approaches a blockaded port does not know or cannot be presumed to know of the blockade, the notifi cation must be made to the vessel itself by an officer of one of the ships of the blockading force. This notification must be entered in the vessel's log book, with entry of the day and hour, as also of the geographical position of the vessel at the time.
A neutral vessel which leaves a blockaded port must be allowed to pass free if, through the negligence of the officer commanding the blockading force, no declaration of blockade has been sent to the local authorities, or if, in the declaration as notified, no delay has been indicated.
Art. 17. The seizure of neutral vessels for violation of blockade may be made only within the radius of action of the ships of war as signed to maintain an effective blockade.
Art. 18. The blockading forces must not bar access to the ports or to the coasts of neutrals.
Art. 19. Whatever may be the ulterior des tination of the vessel or of her cargo, the evi dence of violation of blockade is not sufficiently conclusive to authorize the seizure of the ves sel if she is at the time bound toward • an un blockaded port.