Now it is clear that for practical purposes the British Empire has only two land frontiers--the one on the north-west of India, the other on the south of Canada. It is therefore obvious that an attack upon any other part of the Empire must be conducted over the water. Even if there were attack upon the land frontiers, the enemy would undoubtedly operate also upon the ocean for the purpose of breaking the communications between the different parts of the Empire. He would seek to destroy the steamers and cables, so that one part of the Empire might not send help to another part. The first interest, therefore, of every section of the British Empire, is that there should be peace upon the ocean, so that the steamers may ply regularly and that the cables may not be disturbed. If the British Navy were defeated, the Empire could no longer exist. Do you remember the map which was shown early in the first lecture, giving the lands of the world in black so that they might contrast with the blue sea? And do you remember that the object of that map was to prove that all the lands of the world, even the greatest continents, are surrounded by the ocean, and are in reality islands? The ocean, therefore, is a single vast sheet of water covering three-quarters of the globe. A squadron of ships can in a voyage of about a month go to any point on the coasts of the world. Clearly then one Navy will suffice for the sea defence of every land in the British Empire, for if the enemy’s fleet is attacking one part, a British fleet can go to that part, sure that the opponent fleet is not in any other part of the world. But if the enemy divided his fleet then the British fleet can be divided to meet him. The battleships of Britain are moving fortresses, which can be carried over three-quarters of the world instead of being fixed at a single point as they would be if they were on land. I need hardly remind you, however, that a ship can only keep the sea while it has coal and food. Therefore, although one Navy is enough--providing it be strong--for the defence of every part of the British Empire, yet it is essential that wherever a British fleet may go it should find at no great distance British ports ready from time to time to equip it afresh. It is in Britain’s power in one short month to send a great fleet of battleships to any part of the ocean where they may be required. They would arrive ready for action, because at each stage of their journey there would be British harbours to replenish their stores and to make good defects. On the direct route to India, for instance, we have Gibraltar, Malta, and Aden. On the alternative route, round the Cape of Good Hope, are Sierra Leone, Ascension, St. Helena, Simonstown, and Mauritius. Therefore, while the Navy defends all parts of the Empire, each part has also a duty to the Navy.