Now every new engine of war--and as a long-range weapon the modern gun is such--creates a double problem. There is the art of using it in attack; there is the art of countering it when it is in the enemy’s hands. With every new development, then, the Navy has to learn a new offensive and a new defensive. In the matter of guns, there is but one defensive that can be perfectly successful. It is to develop a method of using them so rapid, so insistent, and so accurate that the enemy’s guns will be out of action before they can be employed against us. Failing this there is a secondary defensive, viz., to protect ships by armour. Finally, you may keep out of range of the enemy’s guns by turning or running away. The adoption of armour calls for no perfection either of tactical organization or technical practice. It is a matter which can be left to the metallurgists, engineers, and constructors. The purely naval policy, then, would have been either to develop the use of guns offensively, which, as we have seen, must also be the best defence, or with a purely defensive idea, solely to enjoin the tactic that will avoid the risks inseparable from coming under the enemy’s fire. To the country that was completing nearly two battleships to any other country’s one, that aspired to command the sea, that hoped to be able to blow any enemy fleet out of the water if it got the chance, it would seem obvious that there could be only one gunnery policy; to wit, push the offensive to the highest possible extent. Again, the distinguishing feature of submarines is their capacity to approach the strongest of vessels unseen and then, in waters superficially under hostile command, to strike with the most deadly of all weapons. As they gained in speed and radius of action, it became obvious that wherever a fleet might be--whether at sea or in harbour--it must, unless it were protected by effective passive defences while in harbour, and by numerous mobile guards when at sea, be exposed to this insidious and, if successful, deadly form of attack. The basic supposition of British naval policy has been to maintain a fleet sufficiently powerful to drive all enemy’s craft within his harbours and defences. The proposition has only to be stated for it to be clear that the navy could not have expected, except in rare circumstances, to have any targets for its submarines, whereas it was as certain as any future thing could be, that every British ship would be a constant target for the enemy’s submarines. British policy in regard to submarine war should, then, have been mainly, if, indeed, not wholly, defensive. Thus, if there was one form of _offensive_ imperatively imposed on us, it was that of naval artillery; and if there was one form of _defensive_ not less imperatively incumbent, it was the provision of adequate protection against submarines.