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Documentary Histories

Plan to Prevent a Submarine Raid

AREA:              GENERAL

SUB AREA:           <Western Atlantic>


SOURCE:             Op. Plan. File No. 0118

                   (Approved 18, July, 1918)________________

DATE:              JULY 18, 1918.

MISSION**           To forestall and counter a raid of enemy submarines on the Atlantic Coast of the United States.

Enemy forces, motives and probable action.

The enemy has available a certain number, about ten, of the cruiser type of submarines having a cruising radius of approximately 17,000 miles on the surface at economical speed, and an offensive armament of two six-inch guns, torpedo tubes bow and stern, and ability to carry and lay a limited number of mines, and carry about 20 reserve torpedoes.

One of these vessels has just completed a raid on the Atlantic Coast.1 Its operations were as follows: Approached coast to the northwest Cape Charles Lightship on May 25,1918, and from then until June 2,1918 operated in this area, sinking several vessels, but taking precautions to keep its presence and operations secret by keeping crews of sunken vessels on board the submarines. On June 2, 1918, realizing that impracticability of maintaining secrecy any longer, the submarine, having placed its mines near Overfalls Lightship,2 commenced an aggressive campaign against defenceless vessels, standing off the coast, and to the southward to avoid the offensive action of the submarine chasers, which by their limited radius, etc., are restricted to useful operations near a base.

After operating in the area between 36º and 38-30 N Latitude, and 72º and 74º W. Longitude for about 10 days, the submarine began his return to Europe via the trade route, sinking vessels en route as practicable.

In the operations off this coast, it is noted that the submarine took no chances against vessels having offensive characteristics. That he treated crews of sailing vessels taken on board the submarine and retained as prisoners with great courtesy and kindness, and there was at all times evidence of abundant food and other refreshments. These crews were offered cigars and wines and given excellent food.

It is believed that the motives of the enemy in sending the submarine to operate in this area were as follows:

(a)  To weaken the morale of the American people, and thus

(b)  To prevent or delay the transport of troops;

(c)  To interfere with the transport of supplies;

(d)  To divert to duty on this coast offensive vessels intended for duty in foreign waters;

(e)  By treating personnel with elaborate courtesy, to institute a form of propaganda to convince the inhabitants of this country, especially those of German descent, that reports of cruel and barbarous treatment of prisoners were untrue or exaggerated;

(f)  To afford information to govern action when future raids are planned.

          While this raid accomplished very little in regard to the main issues involved, it caused some damage and disclosed our limited offensive capabilities to counter such operations. The operations of the offensive vessels of the United States and her allies in the so-called submarine zones has greatly limited and reduced the effective work of the enemy submarines, and has made advisable a change of policy. It is considered possible that an intensive submarine campaign be inaugurated on the Atlantic Coast of the United States.

          It is believed that the enemy’s most probable course of action will be to organise an operation of three or four submarines, objectives as follows:-

(1)  To the Eastward of Nantucket Lightship,

(2)  Vicinity of the Capes of the Chesapeake, or Capes of the Delaware,

(3)  To the Eastward of Cape Hatteras,

(4)  Florida Straits,

(5)  Gulf of Mexico,

the submarines to begin operations simultaneously in their allotted areas in order to produce the greatest effect upon the morale of the American people.

          Bases, fixed or mobile, might be provided which would permit the submarines to replenish supplies and renew their aggressive work. It is considered more probable, however, that the submarines will be directed to return home after their first offensive, carrying with them captured war materials such as copper, etc., that are required by Germany in the manufacture of war supplies.

Our own forces -- Methods open to us.

          Practically all available destroyers are required to carry out our policy of sending destroyers abroad as soon as possible, and to escort our convoys from this coast.

          The other types of vessels have been allocated to important war work, leaving available to counter this probable enemy offensive, a number of 110 ft submarine chasers and a number of submarines.

          It is essential that these vessels should be used to their maximum advantage to successfully counter a well-planned offensive.

          The function of the small submarine chaser is to hunt out and destroy submerged enemy submarines. A hunting group of submarines chasers consists of three vessels, and the groups should be employed in areas contiguous to a base, and in accordance with well defined tactics.

          In order to properly discharge their true function, chasers must be fitted with listening and other special equipment, and the crews indoctrinated.

          Submarines can be operated in an area farther away from the coast, and can remain in such areas for an indefinite period of time, provided stores could be replenished, and some means provided for relaxation of personnel and minor repairs. Submarine chasers and submarines should never be assigned to the same operating area.

          There are also available a certain number of seaplanes and dirigibles.


          (1)  To employ air craft and available destroyers and fast vessels when not required for convoy, in scouting out areas adjacent to the coast, to determine as soon as possible evidence leading to the detecting of enemy submarine operations;

          (2)  To expedite the fitting out of submarine chasers with special equipment, allocate them to bases and assign to the various groups for search definite areas adjacent to the coast.

          (3)  To employ the submarines offensively, for hunting out areas to seaward of areas assigned to chasers, and adopt some method of maintaining these vessels in allotted areas, for as long a time as possible, and maintaining communications.


          The tactics of submarine chasers calls for their operation in groups of three.

          Operating in this way they are able to follow a submerged submarine underway and reach a position favorable for attack. In operating in groups they would have a combined armament of three 3” guns and machine guns, which would probably prevent a submarine from deliverately trying to come to the surface during an attack.

          It is advisable to have groups of submarine chasers backed up by a vessel having gunpower sufficient to make it necessary for the submarine to submerge, but in view of its policy as demonstrated by previous operations, to take no chances on the surface against armed vessels, and in view of the small target presented by the chasers it is not believed that it will seek an engagement on the surface with a submarine chaser group.

          The following assignment of bases and operating areas are recommend:--




Boston, Mass.



Provincetown, Mass.



Menemsha Bight,Martha’s Vineyard......

44-91 & 92



Great Salt Pond,Block [Island]

44-99 & 100


Long Island, East End

44-98 & 56-08


New York

44-97 & 56-07


Lewes, Del.



Hampton Roads, Va.

56-25, 26, 35,36, 45, 36.


Beaufort, N. C.

56-54 & 55


Charleston, S. C.

56-71 & 81


Key West, Fla

67-59 & 60


Dry Tortugas

67-57 & 58


          The submarines should be allocated to such places as will permit of their being able to occupy quickly probable areas of enemy operation to seaward.

          By a careful study of the Atlantic trade routes the following locations appear to be the centres of probable enemy submarine operations:-

          Latitude                     Longitude

          40-30 N.                     66º W.

          38-30 N.                     63º W.

          38-30 N.                     71º W.

          35-00 N.                     73º W.

Two submarines from Key West should also be stationed on the east side of Florida Strait. They would not need a base ship.

          In order that the submarines may operate efficiently in any area selected, it is recommended that submarine hunting groups be organized as follows:

          Each group to consist of two submarines and a large schooner of the usual coastwise type serving as a base and supply ship for the submarines.

          After reaching the assigned area one submarine is to remain near the supply ship and the other submarine to be assigned to patrol distant parts of designated area.

          In the previous operations of the enemy submarine there has been no effort to avoid sailing vessels. If the same policy is employed in subsequent raids, it will afford an excellent opportunity for attack by the submarine in company with the supply ship. If a different policy is employed it may be possible to convey information to the other submarine in the group which will enable it to make a successful attack.

          The submarines employed should be so painted as not to be silhouetted against the schooner.

          The schooner should have a radio set with a portable antenna which could be hoisted in the event that SENDING became imperative but they should normally have up a single wire, lightly insulated, connected to a receiving set on which continuous watch should be stood. The schooner should also be well equipped with listening sets as sailing vessels make ideal listening stations. An efficient masthead lookout should be maintained during daylight.

          The schooner should carry a supply of food, stores, water, a few submarine engine spares and two spare battery cells for each submarine. She should also have a work bench with vise and hand tools. In addition, if they could have one lathe (belt driven) 18” swing, 6 ft gap; one drill press 24” radius, drills up to 3”; one power grinder, the schooner would afford facilities for making minor repairs and prevent the return of a submarine from station to repair minor casualties. A small gasolene engine could run these tools. These tools are not indispensable but would furnish good insurance against discontinuity of patrol. The question of carrying fuel in the schooner and refueling in good weather should be carefully considered. No armament will be provided for schooner except the usual rifles and revolvers;


          One submarine would remain on continuous patrol in the assigned area, submerged during daylight and on the surface at night.

          To prevent mistakes this boat would never approach the base ship except on the surface and then only at prearranged times. Preferably he would not approach the base ship oftener than once in 48 hours.

          The second submarine would remain normally alongside the base ship. It should be in the awash condition with enough officers and crew on board at all times to submerge instantly and attack.

          The base ship should be commissioned and officered and manned by naval personnel in inconspicuous uniforms.

          Continuous radio and listening watches should be stood on the base ship. Personnel of the submarine should not be allowed on deck of the schooner during daylight and should be aboard of the base ship only so much as to insure getting sufficient relaxation and rest.

          In the event of sighting a submarine, or submarine periscope, the submarine alongside the base ship would submerge instantly and proceed to attack. If enemy submarine comes to the surface the crew of base ship should wait in the expectation of being called on to abandon ship.


     1ST. Group – N-3and N-4 and schooner fitted out by Comdt. Second Naval District,3 and based at Great Salt Pond, Block Island.

     2nd. Group – M-1 and N-7 and schooner fitted out by Comdt. Fourth Naval District4 and based at Cold Spring Harbor, Cape May.

     3rd. Group L-5 and L-8 and schooner fitted out by Comdt. Fifth Naval District5 and based at Lynnhaven Roads.

     It is believed that these schooners can all be fitted out and assigned without exciting any suspicion that they would be used in sea operations. Their known functions to be base ships for submarines.

     The information regarding their special use should be known only to the Commandants of Naval Districts and their Chiefs of Staff.

     It would be quite the logical thing to do to acquire schooners of this character to be used as stationary supply ships.

     In the event of the approval of a plan of operation of this general nature, it is proposed that a representative of the Chief of Naval Operations should visit the Commandants of the Districts concerned and inform each one in confidence regarding the plan in order that the secrecy may be maintained.


     The mission of our coast submarines is to destroy enemy submarines that visit this side of the Atlantic.

     This mission can be accomplished only be stealth.

     Therefore, enemy submarines must be observed before they can observe our submarines.

     Under ordinary circumstances to accomplish this purpose our submarines should remain submerged and use their periscopes.

     Since the range of vision of a periscope is small there appears need of a special observing ship.

     If this ship were an ordinary merchant vessel it could observe without exciting suspicion and would serve the additional purposes of a bait for the enemy and a mother ship to our submarines.

     An ordinary coasting schooner properly equipped would serve all purposes and could keep the sea indefinitely.

     Manned with a navy crew specially selected for sailing ship experience and carrying a portable radio set it might accompany a submarine and remain at sea for such periods of time as enemy submarines are on our coast. Its status would be purely that of a mother ship which incidentally acts as observer. It should carry a small machine shop, spare parts and extras and fuel for its own submarines.

     Each mother ship would have two submarines; one to remain near by on the surface but ready to submerge on the sighting of any vessel from the schooner’s crow’s nest; the other to operate within the prescribed area of the district on war warnings received from the schooner, returning at intervals to the mother ship at predetermined times.

/s/ Wm. Pratt_________________________Captain, U. S. Navy.

/s/ W. Evans__________________________Captain, U. S. Navy.

/s/ I. W. Warren (?)__________________Captain, U. S. Navy.

/s/ J. F. Tompkins____________________Captain, U. S. Navy.

/s/ K. M. Bennett6__________________Captain, U. S. Navy.

     The general plan as outlined herein is approved.

     Three submarine hunting groups will be organized as soon as possible.

     Base ships (schooners) to be allocated as follows:-

          (a)  Great Salt Pond, Block Island.

          (b)  Delaware Breakwater.

          (c)  Hampton Roads or Lynnhaven Roads.

     That part of the plan regarding the allocation of hunting groups of submarine chasers is approved in principle, but is not to interfere with the employment of these vessels for convoy purposes when required.

     It is further to be distinctly understood that for the present these base ships are in no sense “mystery ships” as is commonly understood by that term. They are unarmed mother ships for our submarines carrying a naval personnel, regularly commissioned, and carrying the marks of a commissioned naval ship, which relies for her protection upon the presence of the accompanying submarine which she mothers.

/s/   W. S. BENSON.

Source Note: D, DNA, RG 45, Entry 520. A handwritten note at the top of the first page reads: “Copy filed in ir-9c” and “IV-A” is written in further to the right on the same line.

Footnote 1:The U-boat in question was the U-151. For more on its activities off the American coast and the U.S. response, see: Warning, 3 June; Benson to Sims, 3 June; Benson to Sims, 7 June; and Steps to Protect Shipping, 15 June 1918. A detailed account of U-151’s cruise is provided in Bell, When the U-Boats Came to America: 23-92.

Footnote 2: Lightship Overfalls is located in Lewes, Deleware.

Footnote 3: Comm. James P. Parker. This district was headquartered in Narragansett, RI.

Footnote 4: Capt. George F. Cooper, Philadelphia, Pa.

Footnote 5: RAdm. Nathaniel R. Usher, Norfolk, Va.

Footnote 6: Capt. William V. Pratt, Assistant Chief of Naval Operations; Capt. Waldo Evans, Office of Naval Operations; Capt. I.W. Warren; Capt. John T. Tompkins, Office of Naval Operations; and Capt. Kenneth M. Bennett, Office of Naval Operations.

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