merchant shipping, and the indispensable service, which it performed to the cause of civilization, I have already described. But the fact remained that there could be no final solution of the submarine problem, barring breaking down the enemy moral, until a definite, direct method of attacking these boats had been found. A depth charge, fired from the deck of a destroyer, was a serious matter for the submarine; still the submarine could avoid this deadly weapon at any time by simply concealing its whereabouts when in danger of attack. The destroyer could usually sink the submarine whenever it could get near enough; it was for the under-water boat, however, to decide whether an engagement should take place. That great advantage in warfare, the option of fighting or of running away, always lay with the submarine. Until it was possible for our naval forces to set out to sea, find the enemy that was constantly assailing our commerce, and destroy him, it was useless to maintain that we had
discovered the anti-submarine tactics which would drive this pest from the ocean for all time. Though the convoy, the mine-fields, the mystery ships, the airplane, and several other methods of fighting the under-water boat had been developed, the submarine could still utilize that one great quality of invisibility which made any final method of attacking it such a difficult problem.
Thus, despite the wonderful work which had been accomplished by the convoy, the Allied effort to destroy the submarine was still largely a game of blind man's buff. In our struggle against the German campaign we were deprived of one of the senses which for ages had been absolutely necessary to military operations—that of sight. We were constantly attempting to destroy an enemy whom we could not see. So far as this offensive on the water was concerned, the Allies found themselves in the position of a man who has suddenly gone blind. I make this comparison advisedly, for it at once suggests that our situation was not entirely hopeless. The man who loses the use of his eyes suffers a terrible affliction; yet this calamity does not completely destroy his usefulness. Such a person, if normally intelligent, gradually learns how to find his way around in darkness; first he slowly discovers how to move about his room; then about his house, then about his immediate neighbourhood; and ultimately he
