If the ocean paths used by our merchant ships—­the trade routes or sea communications of the United Kingdom with friendly or neutral markets and areas of production—­could be kept open by our navy, that is, made so secure that our trade could traverse them with so little risk of molestation that it could continue to be carried on, it resulted as a matter of course that no sustained attack could be made on our outlying territory.  Where this was possible it was where we had failed to keep open the route or line of communications, in which case the particular trade following it was, at least temporarily, destroyed, and the territory to which the route led was either cut off or seized.  Naturally, when this was perceived, efforts were made to re-open and keep open the endangered or interrupted communication line.

Napoleon, notwithstanding his supereminent genius, made some extraordinary mistakes about warfare on the sea.  The explanation of this has been given by a highly distinguished French admiral.  The Great Emperor, he says, was wanting in exact appreciation of the difficulties of naval operations.  He never understood that the naval officer—­alone of all men in the world—­must be master of two distinct professions.  The naval officer must be as completely a seaman as an officer in any mercantile marine; and, in addition to this, he must be as accomplished in the use of the material of war entrusted to his charge as the members of any aimed force in the world.  The Emperor’s plan for the invasion of the United Kingdom was conceived on a grand scale.  A great army, eventually 130,000 strong, was collected on the coast of north-eastern France, with its headquarters at Boulogne.  The numerical strength of this army is worth attention.  By far the larger part of it was to have made the first descent on our territory; the remainder was to be a reserve to follow as quickly as possible.  It has been doubted if Napoleon really meant to invade this country, the suggestion being that his collection of an army on the shores of the Straits of Dover and the English Channel was merely a ‘blind’ to cover another intended movement.  The overwhelming weight of authoritative opinion is in favour of the view that the project of invasion was real.  It is highly significant that he considered so large a number of troops necessary.  It could not have been governed by any estimate of the naval obstruction to be encountered during the sea passage of the expedition, but only by the amount of the land force likely to be met if the disembarkation on our shores could be effected.  The numerical strength in troops which Napoleon thought necessary compelled him to make preparations on so great a scale that concealment became quite impossible.  Consequently an important part of his plan was disclosed to us betimes, and the threatened locality indicated to us within comparatively narrow limits of precision.