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Captain William V. Pratt, Acting Chief of Naval Operations, to Vice Admiral Albert Gleaves, Commander, Cruiser Force

MDH                          Copy

S-9-105 DNC                 SECRET

N A V Y  D E P A R T M E N T


30 October, 1918.

From:   Chief of Naval Operations.

To:     Commander Cruiser Force.

Subject:  Submarine War Warnings.

Reference: (a) Your 1st Indorsement, 25021-18-N (2) WTQ, of 1                     October, 1918.

           (b) ALATL despatch No. 71, of August 12, 1918.1

     1. Reference (b) states that war warnings in plain English will contain only general localities in which enemy activities may be expected, and that in addition to these war warnings, there will be sent out a series of bulletins in “B” code of actual position and nature of enemy contacts and activity, for the use of all military ships at sea and for commandants of naval districts. Stations and schedules on which these bulletins will be sent are indicated.

     2. From the lack of success which the Department has had in being able to predict the enemy’s probable movements in their operations off the coast, it would appear that a merchant vessel at sea with only the war warning position to depend on would not have any greater success. The broadcasting of the last position of the submarine would thus only scatter shipping from this spot and there would be a chance that the vessels concerned would only run into the new position of the submarine.

     3. These general war warnings have been intended primarily for merchant shipping in order that they may increase their vigilance in the area of enemy operations on this coast and not change their courses and thus lengthen their voyage upon hearing a report which may not affect them by the time they reach that vicinity. Vessels are expected to pay attention to ALLO’S|2| in their immediate vicinity, and the Department depends upon the receipt of these ALLO’S by vessels to be the most reliable warning that can be given them by the proximity of a submarine.

     4. The east and westbound routes are laid out with the idea of avoiding collisions, and it is very important that vessels be not scattered away from their course if it can be avoided. It is expected to give warning by radio or through the routing officer abroad to avoid any areas which may become particularly dangerous, but, up to date, there has been no one area more dangerous than another which would warrant the issue of such an order.

     5. The coded bulletin mentioned in ALATL 71 was considered to contain full information for the use of military ships at sea. It was not desired to give any detailed information to merchant ships because it was considered that such would defeat the Department’s system of routing merchant ships safely through areas of enemy activity.

/s/ W.V.Pratt      


Source Note: Cy, DNA, RG 45, Entry 517B. The second page of this two-page memorandum includes the document identifier and the notation “SECRET.” Below the signature is “Fw,” presumably the initials of the typist.

Footnote 1: Neither of these documents has been found but the gist of “(b)” is given in this memorandum.

Footnote 2: “ALLO” was a warning. In a book on the history of the U. S. Navy in France in World War I, Adm. Henry B. Wilson wrote: “Whenever a vessel sighted a submarine she immediately sent out by radio, at full power, in plain language, the word “ALLO”, repeated two or three times, with the position of the sighting. The word “ALLO” is simply the French word for “Hello”. Wilson, American Navy in France, 132.