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Rear Admiral William S. Sims, President, Naval War College, to Rear Admiral William F. Fullam, Commander, Pacific Fleet Reserve Force



February 24, 1917.

My dear old Gloom:

          Your letter of the 15th instant just received.1 It is good business. I am glad to see that you are taking advantage of all the experience and brains in your command to dope out something on this important subject.2

          The North Atlantic Fleet has done considerable work in this line, and it should have been sent to all hands. Perhaps it has been done, but I doubt it. All the Fleet’s work is largely theory,based however upon as many experiments as it is possible to carry out without using gun fire and various devices that would kill people.

          The most up-to-date knowledge on this subject is of course in possession of the British and French Navies. A few days ago, I wrote to Admiral Benson,3 inviting his attention to the importance of this information and stating that it could be obtained only by personal observation, and suggesting that a live young officer be sent abroad and given this as his sole duty. He replied that steps had already been taken to this end. However, we know something of the British methods, and have doped out some for ourselves.

          As you might expect, the best position for look-outs against submarine and destroyer attack is the lowest position in which the look-outs can be maintained. For example, there is our universal experience in the North Atlantic Battleships and Destroyers, that at night a destroyer always makes out a battleship before the battleship makes out the destroyer.

          This is largely due to the fact that the destroyer is silhouetted against the water from observers on the high bridges or superstructures, while the battleship is silhouetted against such light as there may be in the sky from the low positions of the observers on the destroyers.

          It may be taken as a fact that there is no possibility of a vessel, or a squadron of vessels, unaccompanied by a screen, successfully defending themselves against the attack of destroyers at night, and this for the simple reason that, except under very unfavorable conditions, ( a bright moon light on a wrong bearing), the destroyer can approach within easy torpedo range, launch her torpedo, put her helm over and get away before the battleship is aware of her presence. This has been demonstrated right up to the hilt. The answer is that no Commander-in-Chief should ever expose his naked capital ships to torpedo attack at night. The only chance of success against such an attack is an efficient screen which will give warning of the approach of the destroyer, illuminating the boats, and enable the big ships to use effective gun fire.

          As for the most effective use of the battery against submarines and destroyers, that is something which I should like to see very thoroughly discussed. There are many differences of opinion. For example, as to whether certain groups of guns with their search lights should take charge always of certain sections, or whether all guns and lights that will bear, should be used to repell each attack. The latter would be more effective for a single attack; but no intelligent Commander of a Flotilla would make all of his attack at one point, though all the attacks would be made simultaneously if possible.

          With reference to the use of search lights. We have made some rather exhaust<ive>ed experiments in the North Atlantic Fleet, and the unanimous conclusion was that a search light should not be used to find an attacking boat, but only after being notified by the screen of the presence of the boat.

          There were great differences of opinion on this subject, but they were finally resolved by carrying out deliberate experiments with and without the use of search lights. The former experience was an attack by 20 destroyers against the battleship fleet, surrounded by two lines of screens distanced about three miles from the main body and from each other, the individual vessels of the screen being about 4000 to 5000 yards apart.

          In the first attack all of the screening vessels had their search lights on, covering all the space between the individual ships. The idea was that no destroyer could get through the rays of the search light without being discovered. It turned out to be nearly a total failure, as the destroyers got through and delivered a successful attack. On the following night the experiment was tried again with all ships of the main body and screen darkened, and search lights were not used until boats were discovered. The attack was nearly as successful as on the preceding night. On both nights many of the destroyers got within easy torpedo range before being discovered.

<note- They torpedoed the vessels of the screen in all cases, making a hall through which the main attack was delivered.>4

          At that time I was in command of the Flotilla. Of course the battleship people would not believe we did as successful work as we claimed. They more than implied that we fired many red stars when we were outside of torpedo range.

          I therefore suggested to the Commander-in-Chief5 that he allow the attack to be repeated, and authorize the vessels of two divisions of boats to fire actual torpedoes fitted with collapsible heads. This experiment was carried out and a report on the result was made by a board of officers consisting of representatives from the battleships and from the flotilla. The conclusion of this board was that out of 18 torpedoes fired, 11 sure hits were made, and probably 13.

          These exercises convinced the fleet and the department of the exceedingly dangerous nature of a torpedo attack upon a fleet at night, even when it was screened. In all cases there was considerable confusion of gun fire in the fleet. Vessels fired upon each other; they fired at their own silhouettes made by the search lights of other vessels, and they not infrequently fired at nothing, that is, they thought they saw destroyers approaching and opened fire.

          Previous to this time we had had a number of night search attack exercises against the unscreened fleet, and in all cases they were located without difficulty and successfully attacked.

          As to the best me[t]hod of manoeuvering a single unscreened ship, doubtless the British practice is the best. This is based upon the assumption that a submarine will endeavor to place itself in the course of an approaching vessel and fire the torpedo at short range as she passes by. The submarine attack would manifestly be facilitated by a slow speed of the ship and a steady course. It therefore follows that if the ship steams at full speed and changes her course frequently, the chances are largely in favor of her avoiding the attack of any particular submarine. We are very reliably informed that no British ship or British detachment of ships of the grand fleet ever steams at anything but full speed, and that the course is always changed as often as every ten minutes and usually not less than two points. We know of a case of a single ship that went from the North of Scotland to the English Channel carrying out this programme of changing every ten minutes and steaming at full speed.6

          Wherever it is possible, vessels or detachments in the channel or the North Sea, or other areas infested by submarines, are preceded by patrol boats, usually destroyers. One destroyer in advance of a single vessel affords a very considerable degree of protection against the submarine. She usually has sufficient speed to keep ahead of her constantly while steering a zigzaggy course.

          With regard to the protection of any particular area against submarines in daylight, it has been most completely demonstrated that the submarine can be kept entirely outside of such areas, provided there are a sufficient number of patrol boats to make it very dangerous for her to show even her periscope above water.7

          For example, certain areas in the English Channel have been used for the passage, back and forth, of probably five or six million passengers without any of the transports havning [i.e., having] been sunk. Many hundreds of thousands of troops have been brought from Canada and Australia without loss. The same is true of the areas off Alexandria and Salonica.

          Of course the English Channel, as well as all the ports that are now used by British Men of War are protected against submarines by nets. These nets are of various kinds. The one most commonly used is made of strong wire rope ½ inches in diameter. The meshes are about ten or twelve feet square. They are supported from the surface by wooden casks that are attached to the net by lines of ten or fifteen feet long. The sections of the nets are six hundred feet long. At the ends of each net is a heavy metal buoy, held in position by two anchors of about 2000 pounds each. Sometimes one end of the net is held in position by an anchored tug so that when vessels want to pass the tug can lift her anchor and haul the net out of the way. The submarine running into a net of this kind is almost sure to be trapped. Of course all such nets must be protected by surface craft, otherwise they are easily dragged out of position by the enemy. In many cases they are electrically connected with the shore so that anything running into them gives a signal and brings out the patrol boats that are assigned to that area.

          There are other nets of a similar nature, but made of very small wire about 1/8 of an inch in diameter. These are anchored to the bottom with lines less in strength than those of which the net is formed. The net is held in a vertical position by floats on its upper edge, but these floats are ten or twelve feet below the water. These nets are also electrically connected with the shore. It is intended that if a submarine runs into one, it tears it loose from its anchors, and from that time on trails a line of buoys on the surface. Any submarine, when caught in such a net, is notified by Morse code signals that she is being tracked, and is invited to come to the surface or be blown up by a bomb. Such light nets are easily improvised and could be used to great advantage to protect vessels at anchor in certain localities.

          Such nets covering the entrance to a harbor would be a sure means of notification that a submarine was attempting to get in, and she could be attacked by gun fire from surface boats.

<Similar nets with buoys at the top and weights at the bottom are carried by destroyers and dropped in front of a submarine attempting to escape- where the course of the sub. is indicated by the disturbance she causes on the surface>8

          There are doubtless many <other> devices which the British use for resisting submarines, or rather for making certain areas too dangerous for them to operate in, and I only wish we knew all about them.

          It may be just possible that some of the above items might serve as suggestions to your convention. That is my excuse for writing them out.

          If you cannot remain cheerful, be as cheerful as you can.

Always sincerely yours,


Source Note: LTS, DLC-MSS, William F. Fullam Papers, Box 4. Document on: “U. S. NAVAL WAR COLLEGE/NEWPORT, RHODE ISLAND,” stationary.

Footnote 1: This letter has not been found.

Footnote 2: From what Sims wrote later in this letter, it seems the “important subject” was defending a fleet from submarine and destroyer attack.

Footnote 3: Adm. William S. Benson, Chief of Naval Operations.

Footnote 4: This note was handwritten in the left margin.

Footnote 5: Adm. Henry T. Mayo, Commander-in-Chief, Atlantic Fleet.

Footnote 6: Despite what Sims implied here, the British method proved largely unsuccessful in preventing submarines from attacking and destroying ships travelling singly.

Footnote 7: For a detailed description of the United States Navy’s tactical response to the sighting of a submarine, see: Mayo Memorandum to the Atlantic Fleet, 22 March 1917.

Footnote 8: The portion in angle brackets was handwritten at the bottom of the page.