Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to Secretary of the Navy Josephus Daniels
October 8, 1917.
From: Force Commander.
To : Secretary of the Navy (Operations)
Subject: Instructions for Destroyers escorting Troop
Reference: (a) Opnav Cable 590, time group 13004 October.
The subject of escorting convoys is a new one, and I have refrained from issuing any but general instructions as to the operations of destroyers in escorting troop convoys. Instead of issuing standard instructions I have directed that a monthly conference be held of the commanding officers, at which all new ideas would be discussed and tried out as opportunity offers. Before each group of escorting destroyers sails the commanding officers are assembled for a conference as to how their operations are to be carried out. The disposition of destroyers must be altered dependent on the number of destroyers available, the number of ships in convoy, the formation of ships, the state of the sea, the speed of the convoy, visibility conditions and so forth. In general, with six destroyers and a convoy making good twelve knots or more, so that the danger of attack from astern is small, the destroyers are disposed as shown in appended sketch A.
Before starting out from the base, the destroyers are given the number of ships in the convoy, the call letters of the ocean escort, the rendezvous of convoys and their route from the rendezvous, and are instructed to meet the convoy as far to the westward as conditions warrant. The convoy is to continue on the line until picked up by escorting destroyers.
Destroyers are instructed to proceed to the rendezvous on a scouting line so as to cover a greater expanse of ocean and better assist in locating submarines, picking up boat crews, and so forth.
All destroyers have been instructed that for the present the ocean escort (cruiser) will return immediately the destroyers join up. If later the presence of raiders makes it desirable to escort our troopships westward in convoy it may be desirable for the ocean escort to continue into France and return with the same convoy. In this case the ocean escort should take a position as leader of the middle column of the convoy.
Radio is never to be used unless in cases of urgency and when necessary to keep in touch with the convoy Positions are not signaled in latitude or longitude, but by bearing and distance from the rendezvous.
It is the usual procedure for destroyers to assemble to the eastward of the convoy and then proceed west on a scouting line, so as to make certain to intercept the convoy in event of thick weather or any errors in position.
CONVOY UNDER DESTROYER ESCORT
When destroyers join up with the convoy they will take the positions previous assigned by the senior officer of the destroyer escort or as modified by him due to weather, visibility and so forth. The usual positions are shown in appended sketch A.
During daylight hours the destroyers zigzag at an approximate speed of 15 knots, dependent on weather and fuel.
If a submarine is sighted it is expected that the convoy will immediately turn away from the danger and proceed in formation at full speed. On or two destroyers are assigned to attack the submarine while the rest of the destroyers continue with the convoy. Smoke screens may be used if conditions are favorable to assist in screening the convoy. Ordinarily the destroyer assigned to attack the submarine would remain in the vicinity of the submarine until the convoy is on the horizon, so that the attacking submarine would lose sight of the convoy, after which a considerable change of course would be made by the convoy in order to prevent submarines farther to the westward from attacking.
Convoys should not use their guns against submarines while under destroyer escort, except a warning gun to indicate the track of a torpedo or the presence of a submarine. The attack against the submarine will be made by destroyers.
If a ship is torpedoed one or two destroyers are told off to stand by the vessel to save life or assist in salvage work, while the rest of the destroyers continue with the convoy away from the danger. The destroyers usually indicate the presence of a submarine by firing a gun at the spot and blowing six short blasts on the whistle.
Immediately on the return of each destroyer escort the senior officer submits a report of operations together with any recommendations for improvement.
The senior officer present, whether in the destroyer escort or in the ocean escort or in the convoy is in charge of all operations and his orders are to govern.
Owing to the wide experience of destroyer captains in anti-submarine warfare, I quote the following from my report of August 30, 1917:-
“21. As previously reported, it is undesirable for the “convoy commander to attempt to rigidly direct the “operations of his escorting destroyers or prescribe any “definite formations or positions relative to the convoy. “In case of an attack the destroyers, according to their “plan, will operate directly against the attacking “submarine independent of the convoy. Generally speaking, “the best procedure for the convoy is to maintain its “formation but turn away. Care should be taken to prevent “interfering with the destroyers operations by gun fire “from the transports.”
I am pleased to report that convoy commanders have exercised wise discretion in this matter, which has tended to a mutual respect and assisted very largely in the safe escort of our troop convoys.
I trust that the commanders of convoys will keep me advised of any suggestions that may occur to them for the better protection of our troop transports.
Wm. S. Sims