Admiral Henry T. Mayo, Commander-in-Chief, Atlantic Fleet, to Atlantic Fleet.
UNITED STATES ATLANTIC FLEET
U. S. S. PENNSYLVANIA. FLAGSHIP
16 June 1917
From: Commander in Chief.
To: ATLANTIC FLEET.
Subject: Radio communications.
References: (a) C-in-C letter File 816 of 19 April 1917.
(b) D.N.C. Conf. letter of 28 May 1917, subject: Naval Communications with Naval Ships in the Atlantic.
1. Information received from British sources indicates:
(a) That the success of German raiders in eluding British Men-o-War has been largely due to British Men-o-War disclosing their location by the use of radio.
(b) That in several instances merchantmen have been sunk by German submarines due to their location being disclosed by the use of radio.
2. In view of the above, the Commander in Chief again calls the attention of all Commanding Officers to the absolute necessity of reducing radio work to a minimum and directs that the instructions contained in the above references be strictly complied with.
H. T. MAYO
Source Note: Cy, DNA, RG45 Entry 517B. Below Mayo’s signature is the following text: “COPIES: Cmdr. BATTLESHIP FORCE/” PATROL FORCE/” DESTROYER FORCE/” SUBMARINE FORCE/” MINE/” TRAIN/C.O. PENNSYLVANIA/Operations/Director Naval Communications”