Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to Certain Commands in European Waters
U.S. Naval Forces Operating in European Waters
U.S.S. MELVILLE, Flagship.
30 Grosvenor Gardens,
15 July 1918.
From: Force Commander.
To: Chief of Staff, Destroyer Flotillas.
Commander, U.S. Naval Forces in France.
Commander, U.S. Patrol Squadrons based on Gibraltar.
Commander, U.S. Base, Plymouth.
" " " Corfu.
Subject: Concerning British Admiralty Conference on offensive action against submarines attacking convoys.
1. There is forwarded herewith merely as a matter of information certain notes concerning a conference of destroyer officers recently held at the British Admiralty.
2. Attending this conference were representatives from the [Royal Navy] destroyer forces based on Queenstown, Buncrana, Devonport and Milfordhaven.
3. The discussion before the conference indicated the importance of all destroyer escorts having a mutually understood doctrine covering the methods which they should pursue in meeting a submarine attack on a convoy under their protection.
4. It was particularly brought out that the records to date indicate that the probability of two or more submarines operating together, (within, say, ten miles of each other), is very small. There is no authentic record of two submarines actually operating in company and they generally keep separated a much greater distance than ten miles.
5. It was therefore the sense of the conference that at least half of an escort would be justified in temporarily leaving the convoy in order to deliver a depth charge attack, and that at least one or two of the escort should follow up the attack in attempting to injure the submarine or at least to keep it submerged until the convoy was well over the horizon.
6. The method developed by the Devonport destroyers of delivering an attack is, in general, as follows :-
“The destroyer sighting positive evidence of the presence of a submarine immediately hoists a large black flag and proceeds to the attack at 20 knots, taking a course that will permit the destroyer to arrive quickest at the probable position of the submarine. The compass course is hoisted and the destroyer with the black flag is taken as the guide. Other destroyer run parallel courses to the course set by the guide. The guide begins to drop depth charges when in favorable position, and plants marker buoy at the most probable position of submarine. Other destroyers lay parallel lines separated approximately 200 yards, then turn on opposite course and complete the barrage. The standard of speed of all vessels is understood to be 20 knots.
Devonport representatives stated that they had found it very necessary to have a compass signal so that other destroyers could operate freely.”
7. It was pointed out in the conference that the depth charge tactics as originated at Queenstown are particularly adapted for use when but one or two destroyers are available for the attack but that when more are available it was considered advisable to use the Devonport plan of laying a barrage in parallel lines.
/s/ Wm. S. SIMS.