So far, then, the principles on which our naval supremacy was built up are clear. For the enemies with whom we had to deal Anson's system was admirably conceived. Both Spain and France held the communication theory so strongly, that they were content to count as success the power of continually disturbing our control without any real attempt to secure it for themselves. To defeat such a policy Anson's constitution and the strategy it connoted were thoroughly well adapted and easy to work. But it by no means follows that his doctrine is the last word. Even in his own time complications had begun to develop which tended to confuse the precision of his system. By the culminating year of Trafalgar there were indications that it was getting worn out, while the new methods and material used by the Americans in 1812 made a serious rent in it. The disturbances then inaugurated have continued to develop, and it is necessary to consider how seriously they have confused the problem of fleet constitution. Firstly, there is the general recognition, always patent to ourselves, that by far the most drastic, economical, and effective way of securing control is to destroy the enemy's means of interfering with it. In our own service this "overthrow" idea always tended to assert itself so strongly, that occasionally the means became for a time more important than the end; that is to say, circumstances were such that on occasions it was considered advisable to sacrifice the exercise of control for a time in order quickly and permanently to deprive the enemy of all means of interference. When there was reasonable hope of the enemy risking a decision this consideration tended to override all others; but when, as in Nelson's case in the Mediterranean, the hope was small, the exercise of control tended to take the paramount place. The second complexity arose from the fact that however strong might be our battleship cover, it is impossible for it absolutely to secure cruiser control from disturbance by sporadic attack. Isolated heavy ships, taking advantage of the chances of the sea, could elude even the strictest blockade, and one such ship, if she succeeded in getting upon a line of communication, might paralyse the operations of a number of weaker units. They must either run or concentrate, and in either case the control was broken. If it were a squadron of heavy ships that caused the disturbance, the practice was to detach against it a division of the covering battle-fleet. But it was obviously highly inconvenient and contrary to the whole idea on which the constitution of the fleet was based to allow every slight danger to cruiser control to loosen the cohesion of the main fleet.