The British Empire is a modern ocean state just as the United States is a modern continental state. The political and economic cohesion of the British Empire rests upon this one thing, upon the steamship remaining the dominant and secure means of world transport in the future. If the British Empire is to remain sovereign and secure and independent of the approval and co-operation of other states, it is necessary that steamship transport (ocean transport) should remain dominant in peace and invulnerable in war. Well, that brings us face to face with two comparatively new facts that throw a shadow upon both that predominance and upon that invulnerability. One is air transport; the other the submarine. The possibilities of the ocean-going submarine I will not enlarge upon now. They will be familiar to everyone who followed the later phases of the Great War. It must be clear that sea power is no longer the simple and decisive thing it was before the coming of the submarine. The sea ways can no longer be taken and possessed completely. To no other power, except Japan, is this so grave a consideration as it is to Britain. And if we turn to the possibilities of air-transport in the future we are forced towards the same conclusion, that the security of the British Empire must rest in the future not on its strength in warfare, but on its keeping the peace within and without its boundaries. I was a member of the British Civil Air Transport Committee, and we went with care and thoroughness into the possibilities and probabilities of the air. My work on that committee convinced me that in the near future the air may be the chief if not the only highway for long-distance mails, for long-distance passenger traffic, and for the carriage of most valuable and compact commodities. The ocean ways are likely to be only the ways for slow travel and for staple and bulky trade. And my studies on that committee did much to confirm my opinion that in quite a brief time the chief line of military attack will be neither by sea nor land but through the air. Moreover, it was borne in upon me that the chief air routes of the world will lie over the great plains of the world, that they will cross wide stretches of sea or mountainous country only very reluctantly.