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.

The latter points were of great importance. It was always necessary to
keep the Grand Fleet at a strength that would ensure its instant
readiness to move in waters which might be infested by submarines in
large numbers should the Germans decide upon some operation by the High
Sea Fleet. The possibility of action between the fleets necessitated the
maintenance of very strong destroyer forces with the Grand Fleet.

Similarly our oversea military expeditions, with the consequent large
number of merchant ships in