Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, Circular Letter to All Forces
U.S. NAVAL FORCES OPERATING IN EUROPEAN WATERS,
U.S.S. MELVILLE, Flagship,
19 April 1918.
CIRCULAR LETTER NO. 24.
From: Force Commander.
To : All Forces.
SUBJECT: Depth Charge Policy.
1. From many recent reports from escort ships it appears that the recently inaugurated policy of a liberal use of depth charges is still not clearly understood.
2. Vessels were not supplied with greatly increased numbers of depth charges with any idea that they would encounter a larger number of submarines than in the past, but rather with the idea that each submarine encountered should be attached [i.e., attacked] with a much greater number of depth charges.
3. Too much importance seems to be laid upon inflicting nothing short of serious hull damage to the submarine. Many officers appear to have the idea that the only successful method of attack is by –
(a) Direct hits from gunfire or torpedo.
(b) Explosion of mine or depth charge close enough to actually rupture the hull and sink the submarine or cause sufficient leaks to necessitate coming to the surface.
The chances of damage to batteries and internal fittings which will interfere with safe navigation submerged must not be overlooked.
4. The new depth charge policy, that of using depth charges in large numbers similar to artillery fire, whether the submarine is exactly located or not, was inaugurated for the following principal objects.-
First, to increase the chance of causing actual material damage.
Second, to directly attack enemy morale, a factor the importance of which cannot be over-estimated, although its extent is difficult to determine.
5. The number of submarines as compared with the size of the
atoae <areas> over which they operate is so small that few opportunities of attack will be presented and it is mandatory that we make the most of every opportunity.
6. Depth charges must not be treated as torpedoes but rather as shrapnel or shell. They are comparatively easy of manufacture and can, from now on, be supplied in practically unlimited numbers.
7. There should be no limit whatever placed upon their consumption as long as the slightest chance of injuring the enemy is involved.
8. The slightest evidence of a submarine, or what might possibly be a submarine; and particularly the torpedoing of a ship in convoy: whether submarine is sighted or not, should be met by a determined “artillery attack” of depth charges over the general vicinity by all vessels of the escort which are in the immediate vicinity. Such attacks must not be haphazard. They must be studied and planned.
The tactics of such attacks must be developed by the personnel afloat. This is an important duty for “All Hands”.
9. A recent destroyer report is noted in which, having sighted a submarine, the destroyer proceeded full speed to the vicinity of submergence, dropped three depth charges “over the boiling wake,” then turned back and circled the spot, and, as no evidence of damage was apparent, proceeded “on duty assigned”.
In such circumstances it is not understood why a determined “artillery attack” of depth charges was not made in accordance with tactics issued from the Flagship. It would seem to have been fully justified in such an instance to lay “all but three” rather than “but three” depth charges. In fact, with such an indication of his exact position it would appear inexcusable for a vessel with a large supply of depth charges to fail to use them in following up such an opportunity.
10. Self preservation is a human inst<inct>, and by keeping danger continuously on the mind of the submarine commanders their efficiency and nerve is sure to be affected.
11. The effect of the explosion of depth charges, even though distant, is shown by many reports. One destroyer reports that when a charge was exploded more than 1500 yards distant the captain and other officers came up from below convinced that they had been torpedoed. In another instance a large ship was sharply shaken by a charge exploding fully 2000 yards away. Many such instances are recorded and several Allied submarine officers have had their nerve shaken on account of it.
12. It is directed that this letter and Circular Letter No. 16 together with other letters on the same subject be brought to the attention of all officers of the Force.
Wm. S. SIMS.