(2) The prevention of enemy trade in order to interfere with his military operations and to exert economic pressure.

(3) Resistance to invasion and raids.

It was pointed out that the question at issue in each case was the control of sea communications, and in order to attain that control permanently and completely the enemy’s naval forces both above and below water had to be destroyed or effectually masked.  As the weaker German Fleet not unnaturally refused decisive action and as its destruction had hitherto not been achieved, we had adopted a policy of guarding an area between our vital communications and the enemy’s ports, and of guarding the areas through which the trade and transports passed; these were the only methods of frustrating attacks made either by surface vessels or by submarines which succeeded in reaching open waters.  It was pointed out that a combination of these two methods had been in force during the wars of the eighteenth century, blockades being combined with the convoy system and the patrol of local areas by frigates, etc.  History, in fact, was repeating itself.

We mentioned that a close blockade of the German North Sea and Baltic ports presented insuperable difficulties under the conditions of modern warfare, and the alternative of controlling the Dover and Norway-Scotland exits to the North Sea had been adopted.  The former protected the communications of the armies in France, whilst the two combined covered the maritime communications of the world outside the North Sea and Baltic, and if they could be effectively guarded our first two objects would be attained.

So far as the Dover exit was concerned we stated that the narrowness of the waters, with the consequent risk to the enemy from our mines and torpedoes, had so far acted as a deterrent to his capital ships; we had to depend on the light forces at Harwich and Dover to deal with any enemy surface craft attacking the southern area from German ports.

We pointed out that the control of the Norway-Scotland exit depended upon the presence of the Grand Fleet at Rosyth or at Scapa.  This fleet ensured the safety of all the vessels engaged in protecting trade and in hunting submarines outside the North Sea.

Mention was made of the fact that the enemy could not open the sea routes for his own war ships without risking a serious action, and that so far he had shown no inclination to run that risk.  The Battle of Jutland having been fought in the previous year, any future movement of the High Sea Fleet into the North Sea would probably be merely with the object of drawing our capital ships into prepared areas so as to bring about a process of attrition by mines and torpedoes.  Such a movement had been carried out on August 19, 1916.  The reasons which had led to the adoption of the Orkney-Faroe-Iceland blockade line were also explained.