Under these orders the Fleet was disposed strategically so as to block the exits from the North Sea by placing the Grand Fleet at Scapa Flow and drawing a cordon of destroyers across the Straits of Dover supported by the older battleships and protected by certain minefields. These conclusions stood the test of the war. They were never departed from in any important respect by any of the Boards of Admiralty which held office. By this means the British Navy seized and kept the effective control of all the oceans of the world. They did not, however, secure the command of the Baltic, nor the absolute control of the North Sea. We could no longer hope to prevent the enemy from sallying out of his harbours whenever he chose. What use would he make of this liberty, at the outset or during the progress of a war? By what means could we restrict him most effectually? We sought to probe these questions in the naval manœuvres of 1912 and 1913. In 1912 the newly-formed Admiralty War Staff prepared, as an experiment, a plan for an immense cordon of cruisers and destroyers, supported by the Battle Fleet, from the Coast of Norway to a point on the East Coast of England. To a military eye this system appeared unsound, and indeed outside the Admiralty it was generally condemned by naval opinion. I quoted Napoleon’s scathing comment in 1808: ‘Est-ce qu’on a adopté le système des cordons? Est-ce qu’on veut empêcher le contrebande de passer au l’ennemi? Qui est-ce qui peut conseiller au Roi de faire des cordons? Après dix années de guerre doit-on revenir à ces bêtises-là?’ The cordon system was however tried, and was completely exposed and broken down. We then fell back upon a system of what I may call ‘prowling squadrons and occasional drives,’ that is to say, we recognised that we could not maintain any continuous control of the North Sea. The best we could do was to sweep it in strength at irregular intervals and for the rest await the action of the enemy. This clearly involved a considerable risk of raiding forces which might amount to ten or twenty thousand men slipping through and disembarking on our coast. I therefore called for careful individual study to be made of all the different points where such forces could be landed, and what would be the best plans for the Germans to make in each case. At the manœuvres of 1913 Sir John Jellicoe adopted several of these plans for raiding the British coast and put them into execution. He achieved so considerable a measure of success that I thought it necessary to stop the manœuvres on the third day lest we might teach the Germans as well as ourselves.