Shortly after the subject was broached to us we learned that the United States Navy had devised a mine that it was expected would be satisfactory for the purpose of the barrage.  An experienced mining officer was at once sent over by us to inspect the mine and to give to the United States officers such assistance as was possible due to his great knowledge of mining under war conditions.

When he arrived in the United States the mine was still in the experimental stage, but later he reported that it promised to be successful, and in view of the great manufacturing resources in America, it appeared that a considerable proportion of the mines for the barrage could be provided by the United States Navy.  Our own efforts to produce a mine suitable for very great depths were also proving successful and anticipations as to manufacture were optimistic.  Accordingly plans were prepared for a barrage across the North Sea, which were given to Admiral Mayo before he left England on his return to the United States.  Without seriously relaxing our mining operations in the Heligoland Bight, and without interfering with our mine barrage on the Folkestone-Grisnez line, we anticipated at this time that we could provide mines for our portion of the North Sea Barrage by the time that the United States supply of mines was in readiness to be laid.

Admiral Mayo was also furnished with papers dealing at length with our naval policy at the time and the intended future policy, both in home waters and abroad.  Papers were given him relating to our air policy, to the attitude of neutral countries, to the Belgian coast problem, to the blockade, to the defence of trade (including one on the convoy system), to such subjects as the defensive armament of merchant ships with guns, smoke apparatus and mine defence gear, the instruction of the personnel in their use, and the system of issuing route instruction to merchant ships.  An important statement was also supplied giving a detailed account of our anti-submarine policy, both at the time and in the future.

These papers gave the fullest information on the naval problem, and were intended to put the United States Naval Department in a position to appreciate the whole position and its many embarrassments, though we realized that these could be appreciated only by those who, like Admiral Sims, were in daily contact with the problems.  It will possibly be of further interest if mention is made of some of the points to which attention was drawn.

Admiral Mayo, for instance, was informed that British naval policy was being directed in 1917, as during the remainder of the war, to exerting constant economic pressure upon the enemy with a view to forcing him to come to terms.  We also endeavoured to prevent the enemy from interfering with the conduct of the war by ourselves and our Allies.  In the effective pursuit of that policy the duty of the Navy involved: 

(1) The protection of the sea communications of the Allied armies and the protection of British and Allied trade.