Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to the Office of the Chief of Naval Operations
Date May 15, 1918.
Prepared by CS Approved Code B4AR No. 7997
7997 My 7289 Information contained in this cable is given me by the British Admiralty and is necessarily somewhat paraphrased for transmission, but I have every reason to believe it is authentic. There appears to be a reasonable probability that the submarine
s in question may arrive off the United States coast at any time after May twentieth and that she will carry mines.
English experience indicates the favorite spot for laying mines to be the position in which merchant ships stop to pick up pilots. For instance, for Del
e<a>ware Bay the pilots for large ships are picked up south of the Five Fathom Bank Light Vessel. This is <in> our opinion is one of the most likely spots for a submarine to lay a mine.
As regards information possessed by Germans on subject of anti-submarine patrol. They have from various neutral sources information that a patrol is maintained off most of the harbors and especially off Chesapeake Bay. A neutral has reported that the patrol extend<s> as far as Cape Skerry.
It should be noted that except for mine laying , submarines of this class always work in deep water and that the Germans have laid mines in water in depths up to seventy fathoms . So far as is known there is no reason why they should not lay mines in depths up to ninety fathoms.
The foregoing completes the information furnished by British Admiralty. The following is added by me.
There are circumstances which I cannot explain more fully, which render it highly important that nothing whatever should be given out which would lead the enemy even to surmise that we have had any advance information concerning this submarine , even in the event of our sinking her, and that such measures as are taken by the Department be taken as secretly as possible and without public disclosure of the specific reasons.
I venture to remind the Department in this connection that the employment of surface vessels to patrol against this submarine would probably result at best in merely driving her from one area to another , whereas the employment of submarines against her might lead to her destruction. It is suggested that having estimated her most probable
araes <areas> of operation submarines be employed in a patrol as nearly stationary as may be,some of them covering the point south of Five Fathom Bank Light Vessel, remaining submerged during the day with periscopes only showing. Of five submarines certainly destroyed in four days three were torpedoed by British submarines. 7997 22215
Source Note: Cy, DNA, RG 45, Entry 517B. Identification number “16-5-8” appears in the upper right corner. Further identifiers “3/H/C” appear underneath in columnar fashion.