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Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to the Office of the Chief of Naval Operations

          CABLE GRAM SENT     29 November 1917

     To: Opnav, Washington         Ser. No. 1770

1770.     High power radio station Nantes, France, commence<d> operations November twenty-fifth. Station reserved [for] communication [with] ships and Atlantic shore stations beyond range French coastal stations and will not be used [for] communication [with] French coastal patrol. Station will transmit only at fixed hours and will not listen for nor answer calls pending further notice. War warnings will be transmitted seven hours and eighteen hours Greenwich on damped waves using twelve kilowatt spark set wave length twenty-eight hundred metres. Power spark set will shortly be increased to thirty kilowatts and ultimately to one hundred and fifty kilowatts. War warmings [i.e. warnings] will be followed by general or particular signals in cipher for merchant ships conformance confidential circular September first. War warnings are at present for ships within eight hundred miles French coast but not within range of coastal stations ships approaching French coast should start listening when in vicinity twenty-five degrees west longitude. Nantes will transmit at eight hours and sixteen thirty hours Greenwich using continuous wave length nine thousand metres and will repeat immediately using four thousand metres. Continuous wave war warnings are for ships and shore stations atgreat distance equipped for receiving continuous wave and will contain positions submarines and resume situation North Atlantic also movements submarines operating at great distance from shore on routes to America, Azores, Coast of Portugal and Canaries, also signal ciphers in French code to French warships and French Colonial coast stations. Allied authorities can use Nantes for sending to their own vessels using allied ciphers. In case Nantes has nothing to transmit at prescribed hours the word NILSA will be sent. In case after general war warnings there are messages for particular ships or distant shore stations these messages will be preceded by word GEOFF followed by particular call letters. Force European Waters informed and instructed cable Force Commander additional receiving apparatus necessary equip vessels receive Nantes damped twenty-eight hundred continuous four thousand and nine thousand metres. Recommend ocean escorts of convoys be equipped receive Nantes damped twenty-eight hundred and continuous four thousand and nine thousand metres. 13329


Source Note: Cy, DNA, RG 45, Entry 517B.