The danger which confronted the British peoples was never so great in any previous period as it was during the year 1917 when the submarine menace was at its height, and it may be hoped that the lessons to be learned from the history of those months will never be forgotten.  The British Empire differs from any other nation or empire which has ever existed.  Our sea communications are our very life-blood, and it is not greatly exaggerating the case to say that the safety of those communications is the one consideration of first-class importance.  Upon a solid sense of their security depends not only our prosperity, but also the actual lives of a large proportion of the inhabitants.  There is no other nation in the world which is situated as the people of these islands are situated; therefore there is no other nation to whom sea power is in the least degree as essential as it is to us.  Four out of five of our loaves and most of our raw materials for manufacture must come to us by sea, and it is only by the sea that we can hold any commercial intercourse with the Dominions, Dependencies and Crown Colonies, which together make up what we call the Empire, with a population of 400,000,000 people.

What, then, are we to do in the future to ensure the safety of the communications between these islands and the rest of the Empire?  As a matter of course we should be in a position to safeguard them against any possible form of attack from whatever quarter it may come.  So far as can be seen there is no present likelihood of the transport of food or raw materials being effected in anything but vessels which move upon the surface of the sea.  It is true that, as a result of the war, people’s thoughts turn in the direction of transport, both of human beings and of merchandise, by air or under the water, but there is no possible chance, for at least a generation to come, of either of these methods of transport being able to compete commercially with transport in vessels sailing on the sea.  Therefore the problem of guarding our communications resolves itself into one of securing the safety of vessels which move upon the surface of the sea, whatever may be the character of the attack.

I do not desire to enter into any discussion here as to the method by which these vessels can be protected, except to say that it is necessary for us to be in a position of superiority in all the weapons by which their safety may be endangered.  At the present time there are two principal forms of attack:  (1) by vessels which move on the surface, and (2) by vessels which move under water.  A third danger—­namely, one from the air—­is also becoming of increasing importance.  The war has shown us how to ensure safety against the first two forms of attack, and our duty as members of a great maritime Empire is to take steps to maintain effective forces for the purpose.