Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to the Office of the Chief of Naval Operations
18 Dec 1917
2217. Opnav 2197 to your 1591. Reasons for alteration in position of mine barrage are fundamental and as follows: possibility of obtaining a base in Norway is now unlikely. Owing to increased activity of enemy surface craft it is considered that without a base in Norway constant and adequate support to the patrol vessels off the coast of Norway on the Aberdeen – Ekersund line cannot be guaranteed. It is therefore considered essential to move the mine barrage and patrol line further north to the Orkney-Bergen line. The Commander-in-Chief agrees with the necessity for this change under the altered conditions.
Mining of area C. It was not known until Commander Murfin arrived in London that mines and sinkers were being prepared for area C. British mines and sinkers with mooring ropes have been prepared for this area and it is preferred to use them for the following reasons.
First – British mines are considered more suitable for deep mine fields over which ships have to pass because if by mistake the British mine is laid too shallow it automatically becomes safe, whereas it is believed the American mine would still be dangerous.
Second – The Admiralty is confident that the barrage will be completed earlier if British mines are used for Area B and C and American mines for Area A only, as laying of British will begin in January.
Length of antenna – The numbers of patrol craft available will make it impossible to patrol the area to the southwest of the American mine field. It is therefore of great importance that the length of the antenna should be such that a submarine touching the upper extremity should be totally destroyed tending to prove that antenna should not exceed neighborhood seventy feet in length. This will necessitate three lines of mines at different depths in each system. Area A remains as shown in plan on chart number 2182 C|4| but the position in which the first and second system will be laid is enclosed by the following positions
Latitude 59 – 12 N Longitude 0-50 W
Latitude 59 – 00 N Longitude 0-50 W
Latitude 60 – 03 N Longitude 3-10 E
Latitude 60 -15 N Longitude 3-10 E
Mine laying commences at the outer end
The following agreed on in consultation by Admiralty officials myself Commander Murfin and Lt-Cmdr. Schuyler 01318
Source Note: Cy, DNA, RG 45, Entry 517B.