Take, first, the methods of securing command, by which we mean putting it out of the enemy's power to use effectually the common communications or materially to interfere with our use of them. We find the means employed were two: decision by battle, and blockade. Of the two, the first was the less frequently attainable, but it was the one the British service always preferred. It was only natural that it should be so, seeing that our normal position was one of preponderance over our enemy, and so long as the policy of preponderance is maintained, the chances are the preference will also be maintained. But further than this, the idea seems to be rooted in the oldest traditions of the Royal Navy. As we have seen, the conviction of the sea service that war is primarily a question of battles, and that battles once joined on anything like equal terms must be pressed to the last gasp, is one that has had nothing to learn from more recent continental discoveries. The Cromwellian admirals handed down to us the memory of battles lasting three, and even four, days. Their creed is enshrined in the robust article of war under which Byng and Calder were condemned; and in the apotheosis of Nelson the service has deified the battle idea. It is true there were periods when the idea seemed to have lost its colour, but nevertheless it is so firmly embedded in the British conception of naval warfare, that there would be nothing left to say but for the unavoidable modification with which we have to temper the doctrine of overthrow. "Use that means," said its best-known advocate, "when you can and when you must." Devoutly as we may hold the battle faith, it is not always possible or wise to act upon it. If we are strong, we press to the issue of battle when we can. If we are weak, we do not accept the issue unless we must. If circumstances are advantageous to us, we are not always able to effect a decision; and if they are disadvantageous, we are not always obliged to fight. Hence we find the apparently simple doctrine of the battle was almost always entangled in two of the most difficult problems that beset our old admirals. The most thorny questions they had to decide were these. In the normal case of strength, it was not how to defeat the enemy, but how to bring him to action; and in casual cases of temporary weakness, it was not how to sell your life dearly, but how to maintain the fleet actively on the defensive so as at once to deny the enemy the decision he sought and to prevent his attaining his ulterior object.