There was but one cloud on the horizon. The submarine--despite the loss of _Hogue_, _Cressy_, _Aboukir_, _Hawk_, _Hermes_, and _Niger_, and the disturbing rumours that the fleet’s bases were insecure--had been a failure as an agent for the attrition of our main sea forces. The loss of _Formidable_, that clouded the opening of the year, had not restored its prestige. But Von Tirpitz had made an ominous threat. The submarine might have failed against naval ships. It certainly would not fail, he said, against trading ships. He gave the world fair warning that at the right moment an under-water blockade of the British Isles would be proclaimed; then woe to all belligerents or neutrals that ventured into those death-doomed waters. The naval writers were not very greatly alarmed. For four months, after all, trading ships--turned into transports--had used the narrow waters of the Channel as if the submarines were no threat at all. Yet, on pre-war reasoning, it was precisely in narrow waters crowded with traffic that under-water war should have been of greatest effect. These transports and these narrow waters were the ideal victims and the ideal field, and coast and harbour defence and the prevention of invasion, by common consent, the obvious and indeed the supreme functions the submarine would be called upon to discharge. From a military point of view the landing of British troops in France was but the first stage towards an invasion of Germany and, from a naval point of view, it looked as if to defend the French ports from being entered by British ships was just as clearly the first objective of the German submarine as the defence of any German port. Now six months of war had shown that, if they had tried to stop the transports, the submarines had been thwarted. Means and methods had evidently been found of preventing their attack or parrying it when made. Was it not obvious that it could be no more than a question of extending these methods to merchant shipping at large to turn the greater threat to futility? It was this reasoning that, in January and February, made it easy for the writers to stem any tendency of the public to panic, and when, towards the end of February, the First Lord addressed Parliament on the subject, and dealt with the conscienceless threat of piracy with a placid and defiant confidence, all were justified in thinking that the naval critics had been right. And so the beginning of the submarine campaign, though somewhat disconcerting, caused no wide alarm. An initial success was expected. It would take time to build the destroyers and the convoying craft on the scale that was called for, and so to organize the trade that the attack must be narrowed to protected focal points. And as absolute secrecy was maintained, both as to our actual defensive methods and as to our preparations for the future, there was neither the occasion nor the material for questioning whether the serene contentment of Whitehall was rightly founded.