Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to Secretary of the Navy Josephus Daniels
Sent: June 30th 1917. To: Secretary of the Navy (Operations)
Number sixtyfive. First group attacked by submarine longitude twentyfive degrees thirty before arriving at first rendezvous Second group attacked longitude eight (stop) Strongly believe that enemy obtained information regarding movements of destroyers and also movements of troop convoys by intercepting and decyphering despatches sent me in Naval Attache’s code (stop) British experience conclusively proves that simple codes with regular keys can be easily decyphered (stop) sending today code and special keys for use in communication between department and myself (stop) until these are received and placed in use urgently request that all vital communications be sent through British Naval Attache in Admiralty code.
Source Note: Cy, DNA, RG45, Entry 517B. At the top right of the cablegram is an identification number: “8-2-2-a”. Below Sims’ signature is a columnar list indicating where copies of this cable should be filed.