Office of the Chief of Naval Operations to Rear Admiral Marbury Johnston, Commandant, 15th Naval District
<June 11, 1918>
To: Commandant 15th Naval District.
FIRST: From the present and past operations of enemy cruiser submarines it is believed that efforts of these craft are generally now directed against our unarmed merchant ships endeavoring to destroy them by gun fire and bombs. There are very few instances reported where they have attacked with torpedoes our convoys where adequately protected. Characteristics of this type of submarine have been furnished you. At present there are playing between ports in Gulf and to ports out of gulf over 65 United States oil and tank ships in addition to vessels running in that general direction. Approximately half this number runs from Northern Mexican oil Ports and the other half from United States Gulf Ports. The adequate protection of the oil supply is one of the most important logistic questions at present involving both our own forces and the allied fleet. The supply of oil from Tuxpen and Vera Cruz Mexico is especially vulnerable. The most probable undisturbed enemy bases for Gulf operations, according to information received by the Department, are believed to be along the Mexican Coast and the Compeche Bank. The Department is endeavoring to furnish suitable armament to all oil ships plying in the Gulf trade, but in this matter it has been obliged in the past to yield priority to those ships engaged in the trans-Atlantic trade which were certain to encounter submarines.
SECOND: To meet the question of shouldering submarine menace in the Gulf together with such other problems as may be indirectly connected with it, while at the same time not lessening our efforts abroad, the Department has adopted the following general policy. It favors the normal flow of shipping where possible and to attain that end arming of Merchant vessels is best reply against enemy cruiser submarines. Whenever it becomes necessary for purpose of protection to control shipping, intensive escort coordinated with diversion of ship routes where possible is deemed more efficient than any attempts to patrol for submarines other than a close search for concealed bases ashore or afloat. It is believed that the real offensive against submarines other than those made through voluntary contact of the submarine with convoy groups must be conducted for the present through the agency of anti-submarine craft of the chaser type fitted with listening devices and adequately heavy supporting craft armed with depth charges.
THIRD: To enforce detail of this plan the Department has (1st) directed the movement of a heavy supporting force of our destroyers and a division of battleships toward the Gulf, (2nd) has directed the organization and equipment of at least two pairs of mine sweepers for each Naval District, (3rd) will take steps to increase number of chasers in the 8th Naval District with the view to possible use of these chasers in Mexican waters, (4th) will detail four chasers to Cuban waters about 10th July, (5th) has moved U.S.S. CHEYENNE and two submarines to Galveston, Texas and U.S.S. TALLAHASSEE and two submarines to Key West Florida, (6th) has taken steps to organize a supporting land force in case of contingencies, (7th) has organized a hunting group composed of 2 destroyers and 24 chasers ready to move immediately to the area of operations, (8th) and has added to the force of the Commander, American Patrol Detachment, the U.S. Ships MARBLEHEAD, SALEM, ANNISTON, CINCINATTI, RALEIGH, (9th) has instructed the Commander, American Patrol Detachment to coordinate the efforts of the Cuban Navy with those of his own.
Fourth: in the event of actual submarine operations in the Gulf of Mexico, the Commander, American Patrol Detachment will be expected to take charge of the Anti-Submarine operations outside of the District with the force under him, together with such others as may be added, following the general outline indicated by the Department and being guided by information received from the Department from time to time. The Division of Battleships operating in the Gulf will be held in the nature of a supporting force and will not be used for anti-submarine escort except under orders from the Department and then only failing all other means of protection to shipping. Close and complete cooperation between all separate forces involved is expected. Acknowledge. 23011.
Source Note: Cy, DNA, RG 45, Entry 517B.