It is perhaps as well that the nation generally remained to a great extent unconscious of the extreme gravity of the situation which developed during the Great War, when the Germans were sinking an increasing volume of merchant tonnage week by week. The people of this country as a whole rose superior to many disheartening events and never lost their sure belief in final victory, but full knowledge of the supreme crisis in our history might have tended to undermine in some quarters that confidence in victory which it was essential should be maintained, and, in any event, the facts could not be disclosed without benefiting the enemy. But the position at times was undoubtedly extremely serious. At the opening of the war we possessed approximately half the merchant tonnage of the world, but experience during the early part of the struggle revealed that we had not a single ship too many for the great and increasing oversea military liabilities which we were steadily incurring, over and above the responsibility of bringing to these shores the greater part of the food for a population of forty-five million people, as well as nearly all the raw materials which were essential for the manufacture of munitions. The whole of our war efforts, ashore as well as afloat, depended first and last on an adequate volume of merchant shipping. It is small wonder, therefore, that those who watched from day to day the increasing toll which the enemy took of the country's sea-carrying power, were sometimes filled with deep concern for the future. Particularly was this the case during the early months of unrestricted submarine warfare in 1917. For if the menace had not been mastered to a considerable extent, and that speedily, not only would the victory of the Allies have been imperilled, but this country would have been brought face to face with conditions approaching starvation. In pre-war days the possibility of these islands being blockaded was frequently discussed; but during the dark days of the unrestricted submarine campaign there was ample excuse for those with imagination to picture the implication of events which were happening from week to week. The memories of those days are already becoming somewhat dim, and as a matter of history and a guide to the future, it is perhaps well that some account should be given, however inadequate, of the dangers which confronted the country and of the means which were adopted to avert the worst consequences of the enemy's campaign without ceasing to exert the increasing pressure of our sea power upon his fighting efficiency, and without diminishing our military efforts overseas.