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Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to Secretary of the Navy Josephus Daniels



U.S.S. MELVILLE, Flagship.

October 19, 1917.

Reference No. C 1532.


From:     Force Commander.

To:       Secretary of the Navy (Operations).

Subject:   Extension of Atlantic Convoy System.

Reference:   (a) Opnav Cable 704 of Oct. 17, 1917.1

             (b) My cable        of Octo 19, 1917.2

          Although the traffic in the most dangerous parts of the submarine zone is quite well organized into convoys, there still remain a number of areas in the Atlantic where it would be desirable to extend the convoy system, not so much to avoid the present small submarines, but to avoid the large cruising submarines, and especially to limit the losses that may be occasioned by raiders.

          It will be noted at the present time that trade between the United States and Gibraltar is not in convoy, nor is the trade between South American and Dakar, nor that between Cape of Good Hope and Dakar. The trade in the Mediterranean is now being organized on the convoy system.

          During the long nights of winter it is very likely that a number of enemy raiders may escape from the North Sea and operate in the Atlantic.3 The European convoys approaching the British Isles are considered secure against these raiders, unless heavy cruisers are used as raiders. But it should be noted that at the present time all of the westbound convoys from the British Isles are dispersed after crossing the submarine zone, and cross on the westward trip singly. These vessels would all be liable to raider attack, and it is hoped that plans will be in hand before winter sets int to escort convoys all the way across in the event that raiders escape. In addition to the single vessels travelling west, the trade between the United States and Gibraltar, between South America and Dakar and between the Cape of Good Hope and Dakar, together with certain other similar areas is also exposed to raider attack. The extension of the convoy system contemplates that all of this trade will be placed in convoy under ocean escorts. If is were possible to extend the convoy system and to keep vessels in convoy during winter weather, it is evident that the usual type of raider would do very little damage.

          In the extension of the convoy system contemplated, the next convoy to be established is that between the United States and Gibraltar. Separate recommendations on this convoy have already been submitted in reference (b). These recommendations contemplate the establishing of the convoy system between Hampton Roads and Gibraltar without waiting for ocean escorts. It is realized that should a raider come upon a convoy not under ocean escort, considerable damage would be done to the convoy; but at the same time the chances of finding the convoy by a single raider are very small. Furthermore, a raider cannot distinguish from a distance whether a convoy is under ocean escort or not, and the average type of raider that has thus far escaped would no doubt consider every convoy as hostile and to be avoided. However, complete safety would demand that suitable ocean escort be furnished when available.

          Very little experience has been had of submarines attacking convoys not under escort. A number of unescorted convoys are continually passing between Gibraltar and the British Isles and submarines are operating in the vicinity. But thus far only one attack has been made and this was unsuccessful. The great virtue in the convoy is that if the positions of submarines are known the convoy can be routed so as to avoid them. Considering the relatively small number of submarines that are operating, convoys have an excellent chance of missing submarines, even although no warning is received. It is of the first importance that convoys be organized under a Commodore and drilled while crossing the ocean. The British instructions issued to mercantile convoys are available in the Allied shipping offices in the United States, and are considered sufficient to cover the usual problems that confront the Commodore of the convoy.

          The attention of the Department has been invited to the convoy recently escorted by H.M.S. ANTRIM in which 28 vessels executed “Ships right” and “Ships left” with precision, and the escorting vessels reported that not a light was visible in any vessel.4 A great deal of the success of the convoy depends on the manner in which it is indoctrinated and drilled by the Commodore.

          A convoy every 6 days was recommended as the sailing show an average of 3 to 4 ships daily which would make a convoy of 18 to 24 ships. A convoy of this size is considered to be about as large as can be comfortably handled by one commodore. After experience is gained it may be necessary to alter the dates of sailing so as to keep the convoys from being either too small or unwieldy.

          A speed of 200 miles minimum was selected, as vessels slower than this should not trade in the zone.5

          The vessels of the convoy should each have route instructions in the event that they become separated from the convoy and for use if it became desirable to disperse the convoy due to raider activities or for other reasons.

          If enemy battle cruisers should operate against convoys the threat could be met by using battleship escorts for troop and valuable convoys, by temporarily suspending all sailings, or by dispersing at sea and rendezvousing on routes of approach to submarine zone.


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

Footnote 2: The editors believe that Sims was referring to his cable of 16 October 1917. See: Benson to Sims, 16 October 1917.

Footnote 3: The Germans did not send out surface raiders to operate against merchant convoys during the winter of 1917-18.

Footnote 4: For more on the convoy commanded by H.M.S. Antrim, see: Sims to Benson, 10 October 1917; and Diary of Joseph Taussig, 2 October 1917.

Footnote 5: A vessel averaging a speed of 8 knots would travel 200 nautical miles in a day.

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