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 use as transports or supply ships, required a considerable force of destroyers and other small craft.

These commitments greatly reduced the means at our disposal for dealing with the hostile submarines that were attempting to prevent the import of food and raw materials into the country.
Readers of books, and particularly books dealing with war, show a natural avidity for what may be described as the human side of a contest as well as for the dramatic events.