[37] I put this forward purely as a theoretical consideration, because I am not sure that Nelson’s historical blockades fulfilled the condition of not being subject to effective attack. But whether they did or not, the possibilities of destroying the actual as distinguished from the potential effectiveness of a blockade have been entirely altered by the modern appliances of sea-warfare. [38] See p. 44. [39] See the footnote on p. 95. [40] See p. 62. [41] _Letters of Historicus_, p. 132, quoted _ante_, p. 48. [42] _Ibid._ p. 136. [43] President Pierce, cited _Letters of Historicus_, p. 132. [44] As an illustration of the scrupulous exactitude of the appeal to principles by President Wilson in his recent Notes to Germany, I may refer to the distinction he draws in the Note of June 11, between the duty of a neutral Government to enforce its own laws in regard to granting clearances to vessels carrying cargo prohibited by those laws, and the grant of clearances to vessels carrying contraband of war: ‘Performing its recognised duty as a neutral Power and enforcing its natural laws, it was its [_i.e._ the Government of the United States] duty to see to it that the _Lusitania_ was not armed for offensive action, that she was not serving as a transport, that she did not carry cargo prohibited by the statutes of the United States, and that if, in fact, she was a naval vessel of Great Britain she should not receive clearance as a merchantman. It performed that duty. It enforced its statutes with scrupulous vigilance through its regularly constituted officials....’ The performance of these express duties is treated as distinct from the contention of the German Government that the carriage of contraband of war was a violation of American law. [45] _Letters of Historicus_, p. 177. [46] I gather that the meaning of the official answer, dated March 19, to the distinguished chemists who were agitating for the inclusion of cotton in the list of absolute contraband is that their views have been met by the Order in Council. This answer, as printed in the papers of April 6, 1915, was as follows:-- War Office, High Explosives Department, _19th March, 1915_. Institution of Mechanical Engineers, Storey’s Gate, Westminster, S.W. DEAR SIR,--Lord Moulton desires me to acknowledge your letter of the 11th March covering a further letter signed by various gentlemen. Lord Moulton feels that you will be entirely satisfied by the terms of the Order in Council dated the 11th day of March, 1915, which appeared in the Press of the following day. Yours faithfully, J. BAZIRE. [47] Dated January 7, 1807. [48] By Proclamation, August 18, 1915.