The Note declared that the United States would view with anxious solicitude any such general use of its flag; it would afford no protection to British vessels, it would be a serious and constant menace to the lives and vessels of American citizens, and a measure of responsibility for their loss would be imposed on the Government of Great Britain. The reply of the British Government was short and to the point. It dwelt on the fact that the Merchant Shipping Act sanctions the use of the British flag by foreign merchantmen in time of war for the purpose of evading the enemy; that instances are on record when United States vessels availed themselves of this facility during the American Civil War, and that, therefore, it would be contrary to fair expectation if now, when the conditions are reversed, the United States and neutral nations were to grudge to British ships liberty to take similar action. ‘The British Government,’ it continued, ‘have no intention of advising their merchant shipping to use foreign flags as a general practice, or to resort to them otherwise than for escaping capture or destruction.’ Finally, the responsibility for the loss of neutral vessels in such circumstances must fall on the nation which had deliberately disregarded the obligations recognised by all civilised nations in connexion with the seizure of merchant ships. It is clear that the American Note had special regard to the future, and expressed no opinion as to what had occurred in the case of the _Lusitania_. Now she did not fly the American flag to escape capture, but to escape the probability of being unlawfully sunk by a German submarine; for, in view of what had already happened off Liverpool, it is more than probable that a submarine was in lurking for her; to judge from the German irritation at her escape, it is practically certain. What she did, therefore, was in self-defence, and even unlawful things become lawful when they are done to escape extreme danger. The Note refers to the use of a neutral flag to escape capture, the reply justifies it, and the Merchant Shipping Act sanctions it. But, seeing that capture by the enemy is equivalent to destruction, quite apart from the methods of the new piracy, there can be no doubt that the principle of self-defence covers this case also. Self-defence is a natural law which has been embodied in all legal systems, and Nature has sanctioned it as a special plea. ‘Protective coloration’ is the device by which she defends the weak from the unscrupulous strong; it is ‘mimesis,’ a mimetic change, which Nature not only approves in the case of actually hunted animals, but also and mainly devises for those which are likely to be hunted. So the analogy is complete, and the change of her ‘colours’ by the _Lusitania_ to escape the lurking danger of the submarine stands justified by both natural and human law. I prefer this explanation to the theory of the _ruse de guerre_.