tenacity with which Cornwallis maintained the blockade at Brest, and by the instinctive sagacity with which other commanders of the several blockading and cruising squadrons nearly always did the right thing at the right moment, divined Barham's purpose, and carried it out almost automatically. Practically, Napoleon was beaten and his projected invasion of England was abandoned many weeks before Trafalgar was won. But the command of the sea was not thereby secured to England. It needed Trafalgar and the destruction of the French and Spanish Fleets there accomplished to effect that consummation. England thenceforth remained in effective and almost undisputed command of the sea, and the Peninsular campaigns of Wellington were for the first time rendered possible. The contrasted phases of the conflict before and after Trafalgar are perhaps the best illustration in history of the vast and vital difference between a command of the sea in dispute and a command of the sea established. Trafalgar was the turning-point in the long conflict between England and Napoleon. CHAPTER III DISPUTED COMMAND--BLOCKADE I have so far treated blockade as the initial stage of a struggle for the command of the sea. That appears to me to be the logical order of treatment, because when two naval Powers go to war it is almost certain that the stronger of the two will at the outset attempt to blockade the naval forces of the other. The same thing is likely to happen even if the two are approximately equal in naval force, but in that case the blockade is not likely to be of long duration, because both sides will be eager to obtain a decision in the open. The command of the sea is a matter of such vital moment to both sides that each must needs seek to obtain it as soon and as completely as possible, and the only certain way to obtain it is by the destruction of the armed forces of the enemy. The advantage of putting to sea first is in naval warfare the equivalent or counterpart of the advantage in land warfare of first crossing the enemy's frontier. If that advantage is pushed home and the enemy is still unready it must lead to a blockade. It is, moreover, quite possible that even if both belligerents are equally ready--I am here assuming them to be approximately equal in force--one or other, if not both, may think it better strategy to await developments before risking everything in an attempt to secure an immediate decision. In point of fact, the difference between this policy and the policy of a declared blockade is, as I am about to show, almost imperceptible, especially in modern conditions of naval warfare. It is therefore necessary to consider the subject of blockade more in detail. Other subjects closely associated with this will also have to be considered in some detail before we can grasp the full purport and extent of what is meant by the command of the sea.