Fourthly, the transfer of enemy troops across the sea must be made impossible; and, in particular, strong flotillas and secondary fleets must be maintained on our own coasts as a guard against possible attempts at invasion. [Illustration: ADMIRAL SIR JOHN JELLICOE (VISCOUNT JELLICOE OF SCAPA).] Fifthly, the transport of our own troops and of those of our Allies must be covered from attack. Under this head alone there were included before the end a number of simultaneous operations entirely beyond example in the history of war. An army of some six millions was passed oversea from the British Isles, from India, from Australia, and New Zealand (and at last more millions from America) to France, to India, to Africa (East and West), to Egypt and Palestine, to Gallipoli and Salonika. Sixthly, the supplies to all these forces, and to most of them simultaneously, had to be maintained for more than four full years and on a scale hitherto unimagined. Seventhly, in several campaigns the Navy had to co-operate in the military operations, notably in Gallipoli, in battles near the Belgian coast, and in the attack on the fortified harbour of Zeebrugge. These seven heads cover every recognized department of naval war; but it must be added that when this latest war changed its character and became an unrestricted submarine campaign, new developments were necessary and were immediately carried out. Under the second and third of the above headings, an entirely new fleet of mine-sweepers, trawlers, and anti-submarine patrols had to be provided, manned, and equipped, to secure the safety both of our ships of war and of our mercantile marine. It will be seen that these tasks, taken altogether, formed a work of which only one Power in the world was capable; while taken separately they appear plainly as seven threads upon every one of which the fate of the common cause depended absolutely. The effort of the Allies in this war was distinguished first by the early heroism of the Belgian, Serbian, and Russian troops; then by the long and desperate endurance of the French, British, and Italian armies; finally, it was reinforced by the large contingent of late-comers from America, and carried to victory by the supreme genius of Foch. But behind and beneath all these lay another force, scarcely thought of at the time, and since almost forgotten, though to it they all owed the very possibility of their military existence. During those four years the British Fleet never ceased to carry great armies over sea; to sweep every ocean clean, and guard the territories along their shores; to shut up the hostile Empire within an impassable barrier. In a word, it retained every day and every night, from the first hour of the war to the last, that control which was the most vital condition of success.