Again, the question arises as to what a submarine can do against a merchant ship when she has found her. She cannot capture the merchant ship; she has no spare hands to put a prize crew on board; little or nothing would be gained by disabling her engines or propeller; she cannot convoy her into harbour; and, in fact, it is impossible for the submarine to deal with commerce in the light and provisions of accepted international law. Under these circumstances, is it presumed that the hostile submarine will disregard such law and sink any vessel heading for a British commercial port and certainly those that are armed or carrying contraband? There is nothing else the submarine can do except sink her capture, and it must therefore be admitted that (provided it is done, and however inhuman and barbarous it may appear) this submarine menace is a truly terrible one for British commerce and Great Britain alike, for no means can be suggested at present of meeting it except by reprisals. All that would be known would be that a certain ship and her crew had disappeared, or some of her boats would be picked up with a few survivors to tell the tale. Such a tale would fill the world with horror, and it is freely acknowledged to be an altogether barbarous method of warfare; but, again, if it is done by the Germans the only thing would be to make reprisals. The essence of war is violence, and moderation in war is imbecility. It has been suggested that it should be obligatory for a submarine to fire a warning gun, but is such a proceeding practical? We must bear in mind that modern submarines are faster on the surface than the majority of merchantmen, and will not necessarily need to dive at all. Therefore, as the submarine would in most cases be sighted, and as she has no prize crew to put on board, the warning gun is useless, as the only thing the submarine could do would be to sink the enemy; also, the apparently harmless merchant vessel may be armed, in which case the submarine may but have given herself away if she did not sink her. The subject is, indeed, one that bristles with great difficulties, and it is highly desirable that the conduct of submarines in molesting commerce should be thoroughly considered. Above all, it is one of overwhelming interest to neutrals. One flag is very much like another seen against the light through a periscope, should he have thought it necessary to dive; and the fear is natural that the only thing the officer of the hostile submarine would make sure of would be that the flag seen was not that of his own country.