Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters Circular
U.S. NAVAL FORCES OPERATING IN EUROPEAN WATERS
U.S.S. MELVILLE, Flagship,
( C O P Y ) 9 April 1918.
From: Force Commander.
To: All Forces.
CIRCULAR LETTER NO. 16.
SUBJECT: Offensive action against submarines.
1. The Force Commander wishes to impress on all ships the all important fact that their major mission is always offensive attack on enemy forces whenever the slightest opportunity offers.
The best protection of a convoy is a determined and persistent attack on the attacking submarine. The U-53 recently followed a convoy for over two days making a series of attacks, and seriously damaging four ships of the convoy.
2. It has been estimated, based on certain past records, that the destruction or disablement of one enemy submarine represents the saving of a minimum of 50,000 tons of shipping in the year immediately following such loss.
3. Our opportunities for actual decisive attacks on enemy submarines are so few that it is vitally necessary that the maximum advantage should be taken of every opportunity of offensive action, no matter how meagre the resulting evidence of damage may be.
The enemy must be brought to have a wholesome fear of coming within range of our ships.
4. Now that the supply of depth charges is adequate, the policy of using them freely upon every opportunity and upon the slightest evidence of the presence of a submarine, should be prosecuted strenuously.
There is amply evidence indicating that depth charges explode even within a radius of 1000 yards has a pronounced effect on enemy submarine morale.
5. Even when little evidence of the location of course of the submarine is apparent on the surface there is always the possibility of a chance explosion close aboard, but in any case, the effect upon enemy morale is a factor the importance of which cannot be over estimated.
Every opportunity should be taken of consulting with our own and allied submarine officers.
6. The Force Commander has noted with satisfaction various recent attacks of the above nature, particularly those by the DOWNES, ALLEN, BURROWS and ERICSSON. It is also to be noted, concerning the attack of the REID and ISABEL, that although little evidence was obtained at the time to indicate the damage to the submarine, later evidence indicated that this was the submarine which was forced to put into a Spanish port and intern.
7. To meet attacks on convoys in which the submarine is not seen, studies should be made of the zones in which the submarine must have been to have fired, and, where she is likely to be found for a reasonable interval thereafter. All escort vessels on each flank should have plans ready for a prompt and co-ordinate depth charge barrage through such zones of probable submarine location.
8. The only way of improving our methods of attack is to carefully analyze and consider all experience gained. Reports of attacks which have been submitted are, as a rule, rather vague, rendering it difficult to draw conclusions as to the efficiency of the tactics pursued with a view to future improvement.
9. It is therefore directed, in order that all ships may fully profit from the experience gained by the few that have opportunities of attack, that immediately upon arrival in port, more careful and detailed reports, accompanied by sketches, as nearly as possible to scale, be submitted covering all future actions.
Upon receipt of these reports (with sketches) aboard all base flagships, they should be issued to all ships present as soon as possible, and copies sent to the Force Commander and other Base Commanders.
Conference discussions should be held as often as possible to discuss specific past and future tactics.
10. Base Commanders should forecast as far in advance a possible their requirements for increased supply of depth charges in order that manufacture and supply from home may be sure to meet all possible demands in time.
(Signed) Wm. S. SIMS.