Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to Captain William V. Pratt, Assistant Chief of Naval Operations
May 12th. 1918.
PRIVATE AND CONFIDENTIAL.
My dear Pratt,
Many thanks for your tworecent letters, and the encouraging news they contain. Admiral Benson’s telegram assuring me that there was nothing in the rumours to which I referred in my personal letter to him was a great comfort. I hope this incident may now be considered closed. If they will only let things alone as they are now I will have no complaint to make. All I ask is that the responsibility for success should be put up to me, and that my recommendations as to the methods of carrying on the work, and as to the personnel to assist me, should be accepted. Try and fix it so that when officers of considerable rank are to be sent out here that I be consulted.
There is another point, a tactical one, which has caused the Allies a vast amount of unnecessary exertion and expenditure of oil. This has been the unaccoun<t>ably persistent idea that when a submarine has been located in a certain position that it is useful to send out after her one or more destroyers. This idea was responsible for the disastrous patrol system under which we were losing nearly a million tons of shipping a month in April 1917. It crops up from time to time. Only those naval officers who have thought about it carefully realize the utter futility of employing these valuable vessels in that way.
The reason for this is so very simple that its very simplicity seems to prevent it being accepted. It resides in the fact that a submarine can see a destroyer three or four times as far away as the destroyer can see a submarine. Theconsequence is that when the destroyer comes along looking for the submarine, the latter simply ducks under the surface, waits until the danger is passed by, and then goes ahead with the business of sinking ships.
For example, certain submarines are, at certain times, known to be in certain positions off the coast of France or Spain, occupied in waylaying isolated vessels or stragglers from convoys. They are only a couple of hundred miles out. Formerly they used to send out one or more destroyers or sloops, and so forth. Also nothing would have been accomplished if they could have afforded to send out fifty destroyers stationed ten miles apart. They could not have gotten near the submarine without being seen. She would have gone down two hundred feet and plugged along at one-and-a-half knots until they had passed by. It is believed that a submarine is now bumming around off the Azores. If so, he will probably operate at a considerable distance away from the Azores for a reason which I will explain presently. If he is, say, one hundred and fifty miles away from the Azores you can readily calculate how many destroyers would be required to give him any annoyance.
If you knew his approximate position, you could not even embarrass his operations with anything less than a number of destroyers stationed withing sighting distance of each other and covering an area greater than the submarine could cross submerged.
There is no possible mystery or deception about this. If you do not believe it get two fellows to play a chart manoeuvre governed by one rule only, and that is that the submarine can see the destroyers at a distance of, say, fifteen miles, and the destroyer can see the submarine only at a distance of five.
You will find that if you do not get this extraordinarily simple idea solidly into the heads of the people who control the movents of our vessels you will wind up with a whole bunch of destroyers charging up and down our coast burning oil to no purpose while vessels are being sunk here for want of their services. It is exceedingly important that this thing be promptly and thoroughly understood.
We have received word recently that a brand new destroyer has been ordered to go to the Azores and remain there until further orders – this on account of there being one enemy submarine in that neighborhood. This matter is now so well understood over here that an action of that kind on the part of our Department inevitably subjects our Navy to very unfavorable criticism. See if you cannot clear this away.
I referred above to a reason which would oblige the enemy submarine to operate at a considerable distance from the Azores. This is assuming that he knows that there are American submarines in the Azores. Each submarines are the greatest danger to the cruising submarine. Any submarine is a great danger to any other submarine because, even if the submarines are of the same type they have exactly equal chances of destroying each other. When however, our enemy submarine is of the cruiser type and has slow speed, and is very slow in diving he is at a very decided disadvantage in the presence of a smaller and handier submarine.
It is for this reason that the Allies are using submarines against these cruisers when it is possible to do so. When one of them is located off the European coast within striking distance of a submarine, they always send out one or more immediately if they are available. The result is that as soon as the German submarine learns of the presence of an enemy submarine in the area in which he is operating, he promptly moves on to some other area. One of the cruising subs, was torpedoed by a British sub, but unfortunately two torpedoes that struck her failed to explode.
The above to show you that you have already at the Azores the only type of vessels which can be of any effect against the cruising submarine. Dunn has been warned of the presence of these submarines and is alive to the necessity of getting after them.
If one of these cruising submarines appears off the American coast the same tactics should be employed. The destroyer is absolutely of no use against them unless the destroyer accompanies the convoy that the submarine wants to get after.
Of course you know from the information that has been sent in during the past month that these submarines have only once been known to have attempted to attack a convoy. They are too clumsy for that sort of work. I therefore do not think that any convoys are in danger. It is for this reason that outgoing convoys are now ordered to stay together until after they pass the area where these submarines are operating.
I felt there would be no use cabling the opinions given above but that the best way would be to explain the situation to you and let you get in the necessary work to prevent our vessels being uselessly employed.
Always sincerely yours,