Naval History and Heritage Command

Rear Admiral Edwin A. Anderson, Commander, American Patrol Detachment, to the Office of the Chief of Naval Operations

[Extract]

15 June, 1918.

ESTIMATE OF THE SITUATION NUMBER FOUR

MISSION-  To protect shipping in the GULF OF MEXICO and the CARIBBEAN.

THE ENEMY FORCES—THEIR STRENGTH, DISPOSITIONS AND PROBABLE INTENTIONS.

     Since 25 May two German submarines have been operating in the Western Atlantic. The careful and methodical manner in which they are operating and the moderate success they have obtained seem to indicate that it is the intention of the Germans to operate on our Coast from now on.1 When they learn that they have contained two destroyers, 24 submarine chasers, and have drawn at least one cruiser from the Azores and two cruisers and two gunboats from the Pacific Fleet they will have an additional reason to continue their operations off our Coast. It is not probable that the one or two submarines now actually operating off our Coast will enter the Gulf, although they may run through the Florida Straits and along the Coasts of Cuba, Haiti and Puerto Rico on their return passage. However, it would seem extremely probable that the next submarines which arrive will take another step and enter the Gulf of Mexico, where a wonderful opportunity awaits them. Here they will be able to attack the oil trade which is so vital to the Allies. They would also be able to use supply bases off the Campeche Bank and the Mexican Coast, being able to count upon the assistance of numerous Germans in Mexico and to take advantage of the fact that the Mexicans are notoriously pro-German.

     The German cruiser submarines of the U-151 type (formerly U-Deutschland) have a very long cruising radius, about 16,000 miles. They have, on the other hand, the low speeds of 12 knots on the surface and 8 knots submerged. They have a large cargo space in which quantities of supplies of all kinds can be stored, and can thus cruise for several months without any outside assistance at all. They would probably like, however, to replenish their oil supply several times during their voyage. This their agents would probably arrange in either of two ways:

(1) To send out small steamers and schooners loaded with oil to an appointed rendezvous.

(2) To plant large submerged oil tanks in designated positions.

     The former method would seem the simpler of the two, but when the submerged tanks are once placed in position and located by the submarine, this source of supply would be the more reliable as it would be available at any time. The two countries from which such supply expeditions could be started with the best chance of avoiding our forces are Mexico and Cuba. Of the two Cuba would undoubtedly have the greater risks for such an expedition. Cuba in the first place is nominally at war with Germany; a considerable number of Germans have been arrested and interned. It has been possible for the United States to organize an efficient spy system there; the Department of Justice, the United States Food Commission, the United States Army, the Navy Intelligence and American Patrol Detachment all having organizations which cover the entire island. In addition the Cuban Navy, of about fifteen vessels, is patrolling the coasts. A reward of 1000 dollars has been offered for information of enemy activities. For all these reasons there would be considerable difficulty in organizing expeditions to supply submarines from Cuba. On the other hand German agents, in the four years since the beginning of the war, have been able to perfect an efficient organization in Mexico and they should have little difficulty in sending out supplies from anywhere on the coast between Cape Catoche and Vera Cruz. To the northward of Vera Cruz they will have greater difficulty. On the Campeche Banks are numerous localities where submerged oil tanks could be placed and Alacran Reef, Arenas and Arcas Cays provide fine anchorages where they would run little risk of being discovered.

     Experiences has shown that submarines of the U-151 Class when on distant cruises have always been handled with great caution. This opinion is confirmed by the manner in which the operations off the Atlantic Coast have been carried on. This caution on the port of the German commanders to this class may be due to the fact that they believe they can not run any risks of damage to their boats, which might not have a bad effectclose to their bases but which would probably prevent their reaching him if operating at a distance. It also very probably is due to the fact that these boats were designated for use as commercial submarines, and have the slow speed of 8 knots submerged and probably handle very poorly. It is known that the U-Deutschland nearly sank through a casualty during her return from her second trip to the United States. These submarines carry mines and for this reason also are operated with great caution. As the boats of this class are not fitted for operating effectively submerged, they were supplied with the heavy battery of two six inch guns (about 35-calibre)to make them effective as surface raiders. This is the way they usually operate. They cruise in an area some considerable distance from land where there are few patrol craft. Even here they usually attack only unarmed craft and seem to make a specialty of sailing vessels, as their slow speed of 12 knots on the surface makes it difficult for them to run down steamers. For those reasons it does not seem probable that they will operate for extended periods in the Florida Straits, although they may sink a number of vessels while passing through to the Gulf. It seems probable that they will operate about one or two hundred miles to the westward of the western entrance to the Florida Straits where they will be able to work along the routes from Tampico, Tuxpam, Galveston, Port Arthur, and New Orleans to the Straits and also along the routes from these ports to the Yucatan Channel. Another profitable area would be just to the southward of the entrance to the Mississippi. Here trade from Galveston, Port Arthur and New Orleans to the Straits and Yucatan Channel could be intercepted and also trade from Tampico to New Orleans. Another area would be that lying on the route from Tampico and Tuxpam to Galveston and Port Arthur. In all of these areas the submarines would be at a considerable distance from the shore and could not be effectively reached by the district forces.

     The submarines carry mines and would probably mine the entrance to the Panuco River and the moorings off Tuxpam, Lobos Island and Tamiahua, as this could be done at night and with little danger.

     It is not probable that an enemy submarine will act for sustained periods in the Caribbean. It is possible,however, that while proceeding to the Gulf a submarine might operate between Jamaica and Haiti and in Mona,Windward and Crooked Island Passages.

OUR OWN FORCES--- THEIR STRENGTH, DISPOSITIONS AND THE COURSE OF ACTION OPEN TO US

The following forces are now assigned to the American Patrol Detachment:

Ships          Disposition

Raleigh          En route to Key West from South Atlantic.

Cincinnati   En route to Key West from South Atlantic.

Anniston         Repairs completed Norfolk 15 June.

Marblehead  Key West.

Salem      Key West.

Dolphin          Key West, in need of docking and repairs

Albatross         Key West.

Dorothea         Navy Yard ,Charleston repairing until at least 15

                July.

Eagle      Key West.

Annapolis        Tampico, in need of repairs.

Ozark      Tampico, in need of repairs.

Petrel      Galveston

Yorktown         En route Key West.

12 Submarine chasers Key West.

     In addition there are at Galveston the Cheyenne, K-7 and K-8, which might be used in Mexican Waters. Submarine Chasers will be assembled in the Eighth Naval District2 for use in Mexican Waters and an expeditionary force will be prepared.

     The Cuban Navy has been placed under orders of the Commander, American Patrol Detachment by the Cuban Minister of Marine.3 A Campaign Order (see appendix 1 attached) was issued on 19 June in which the vessels were disposed as follows:4

     The following are the main trade routes in the Gulf and Caribbean:

     The Department has indicated the following general policy:

(1) To arm all merchant vessels, particularly oilers.

(2) To keep up to the greatest degree possible the normal flow of shipping.

(3) To spread the shipping over wide areas instead of keeping it to the usual routes.

(4) To attack the submarines with a hunting group of submarine chasers and cruisers.

(5) If necessary,to escort unarmed vessels to protect them against gunfire attack.

(6) To patrol for submarine bases, particularly along the Mexican Coast and Campeche Banks.

     It seems essential to send armed ships on as usual without escort, routing them so as to spread the entire armed shipping over a wide area. As practically all the vessels sailing north from the Panama Canal are armed it will therefore not be necessary to provide naval vessels for the protection of shipping in the Caribbean. A proportion of these vessels, especially those that are not armed, should be sent through Mona Passage instead of the usual route through Windward Passage. Unarmed vessels should as far as possible be sent under the escort of armed merchant vessels.

     The Chief of Naval Operations5 has directed the formation of a hunting group consisting of Salem and twelve submarine chasers. These submarine chasers from the tactical unit for hunting. With each hunting unit it is necessary that there be a ship sufficiently heavily armed to keep the submarine under, as without such support the submarine chasers would have little chance in an action with a submarine on the surface.6

     The submarine chasers have a radius of 1200 miles at 9 knots. <500 wide limit> At higher speeds their radius is much less. <300 miles at 13 knots>7 Their maximum speed is 16 knots. Their engines are moderately reliable, but hardly suited for continuous cruising over wide areas.

     The Hurricane season is beginning. In August, September and October hurricanes form south of the Island of Cuba, pass up through the Yucatan Channel and across the Gulf. In October the Norther Season begins. It is doubtful whether a submarine chaser could live through a hurricane and it would probably be badly damaged by a Norther. It would be absolutely necessary for the chaser to reach a secure anchorage before being caught in a Hurricane and very desirable to do so in the case of a Norther.

     For these reasons it will not be desirable to send the hunting group of submarine chasers at random through the Gulf, which is nine hundred miles long and 500 miles wide. They should operate within a reasonable distance- one to two hundred miles- off some port where they could ride out a storm and where they could refuel. There are safe harbors at Dry Tortugas, Mouth of the Mississippi, Galveston, Tampico, Lobes Island, Arenas Cay, Arcas Cay and Alacran Reef. A gasoline supply could probably be provided for at Dry Tortugas, Mouth of the Mississippi, Galveston and Tampico. A fuel vessel would be required for the other anchorages. The hunting group could shift its base port to port according to the movements of the enemy, but should always keep within a moderate distance of one of the bases. Careful arrangements should be made for sending storm warnings to the hunting group as rapidly as possible.

     In the disposition of the hunting group there are two courses of action: (1) To use the 12 submarine chasers and four of the most powerful vessels of the Detachment as one large hunting group, subdivided into four tactical units, each consisting of three submarine chasers and one large vessel, all units operating in the same area; (2) To divide this force up into three or four groups, each basing at the beginning of the campaign on a port close to an area in which it is probable that submarines will operate, or near where the trade routes converge.

     The first distribution has the advantage that should enemy submarines happen to appear within striking distance of the port at which the group is based the entire group of 12 submarine chasers and four large vessels will be immediately available for operations. On the other hand, should submarines avoid this area the group would have to make a long cruise before being able to commence operations.

     The second distribution has the advantage that at least one tactical unit will probably be within striking distance of the enemy submarines when they commence their campaign in the Gulf. Then, if reinforcements are necessary, the other tactical units may proceed to the scene of operations.

     It is decided to employ the second distribution. As it is most probable that enemy submarines will operate off the Western entrance to the Florida Straits, two tactical units should be based on Dry Tortgas so as to cover this area. Dolphin and Marblehead should be assigned to these units. This allows Dolphin, Detachment Flagship, to be in constant radio communication with Navy Radio, Key West, so that information and orders can be distributed quickly to the entire Detachment. One tactical unit with Raleigh should be based at the Mouth of the Mississippi, so as to be in position to cover the important area to the Southward. The fourth tactical unit, with Salem, should be based on Lobos Island, so as to cover the important area off the Mexican Coast from Tampico to Tuxpam. To this force will be added any submarine chasers which may be sent to Mexican Waters from the Eighth Naval District. Salem, with her fine radio set, will be able to communicate direct with Navy Radio, Key West, vessels operating off the Mexican Coast and Campeche Bank, and the escorts of convoys from Tampico to Galveston. This will establish reliable communication through the entire Detachment, and will be of inestimable value. This arrangement will also place the second senior officer of the Detachment in the most important subordinate command in the Gulf.

     The treatment of unarmed shipping now remains to be considered. There are three courses of action open to us:

(1) To send the vessels on as usual, but spread over a wide area.

(2) To send them on under the escort of armed merchant vessels.

(3) To organize escort systems covering the more important routes.

     If the unarmed ships are sent on as usual the normal flow of shipping will be maintained as nearly as possible. If the vessels are spread over a wide area the risk they run will be greatly reduced. However, there will still be considerable danger. This is the type of vessel the enemy seems to be operating against almost exclusively and he appears to be satisfied, after the first surprise attack, with about one ship a day. By taking a position in a favorable are he would probably be able to accomplish this much without great danger to himself.

     If we hold the unarmed shipping until armed ships leave for the same destination so that one or two unarmed vessels can be under the escort of one or two armed vessels, we interrupt slightly the flow of shipping. Such a slight interruption (one or two days) will not have a bad effect, and would be a slight disadvantage compared with the protection the unarmed vessels would receive against gunfire attack. While this method might be effective for vessels sailing from U. S. Gulf ports, it could not be used for vessels leaving Tampico as no ships are armed.

     There are two escort systems which could be used:

(1)  Two separate convoys escorted by vessels of American Patrol Detachment:

(a) Tampico to Galveston

(b) Mouth of Mississippi to Key West.

and one by District forces between Galveston and Mouth of Mississippi.

(2) One Convoy by American Patrol Detachment from Tampico to Key West, via Galveston and Mouth of Mississippi.

     A convoy of all unarmed ships leaving the Mexican Coast, wherever bound, could be assembled at intervals of four days at Tampico. From there it would proceed northward along the Coast to Galveston under the escort of one vessel. As it would be possible to keep within the 10 fathom curve for the entire journey there would be very little danger of submarine attack. Upon arrival at Galveston the convoy would be broken up. Those vessels bound for Florida Straits and Yucatan Channel should be sent on under district escort to Mouth of the Mississippi to join the convoy proceeding from there to Key West. Vessels for New Orleans, Pensacola and Mobile should proceed under the same district escort. The distance by this route is 515 miles. At eight knots it requires about 64 hours. This allows 32 hours in Galveston for the escort to refuel. At the expiration of this time, that is, 96 hours from the time the convoy started from Tampico, a convoy of all unarmed ships bound for Mexican ports would be made up at Galveston, and would proceed back along the same route to Tampico, where it would be broken up. The escort would then have 32 hours in Tampico before the time for starting the next convoy, which time would be available for machinery repairs. Two vessels would be sufficient for escorts for the Tampico-Galveston Convoy.

     A convoy of all unarmed vessels bound for Florida Straits and Yucatan Passage could be assembled at the Mouth of the Mississippi at intervals of four days from all United States Gulf ports (except Tampa) and from Mexican ports via Galveston. From the Mouth of the Mississippi this convoy could proceed under the escort of one vessel toward the Florida Straits. When a position about one hundred miles from Tortugas is reached the vessels bound for Yucatan Channel could leave the convoy. These vessels should scatter, steam at full speed, zigzag and pass through the Channel during darkness. The convoy should cover the distance from Mouth of the Mississippi to Key West, 480 miles, in about 60 hours, allowing a speed of eight knots. 36 hours would then be allowed the escorting vessel to coal at Key West. At the expiration of this time, or 96 hours from the time the convoy started from Mouth of the Mississippi, a return convoy could be started Key West of all unarmed vessels from Florida Straits and Yucatan Passage bound to all Gulf Ports (except Tampa). This could arrive at the Mouth of the Mississippi the60 hours, where the escorting vessel would have 36 hours to repair machinery. Upon arrival at the Mouth of the Mississippi the convoy should be broken up and sent to their respective ports under district escort or alone. Vessels bound for Mexican ports should be sent to Galveston under district escorts to join the convoy for Tampico. Vessels bound for Galveston and Port Arthur should proceed under the same district escort. Two vessels would be sufficient for the Mouth of the Mississippi-Key West escort. . . .8

     Now consider the second escort system. At intervals of four days a convoy could be assembled at Tampico of all unarmed vessels from Mexican ports, wherever bound. Assume that this convoy proceeds at 2 p.m. on the first of the month under the escort of one naval vessel to the Northward along the Coast inside the 10 fathom curve. It should arrive at Heald Rock Lightship9 after a run of about 64 hours at 6 a.m. of the fourth day, the vessels bound for Galveston and Port Arthur leaving the convoy at that point. At the same time all vessels from Galveston and Port Arthur bound to the Eastward join the convoy and it proceeds to the Mouth of the Mississippi, arriving there after a run of about 36 hours at 6 p.m. of the fifth. At this point vessels for New Orleans, Mobile and Pensacola leave the convoy and vessels from these ports bound to the Eastward join it. The convoy then proceeds to Key West, a run of 60 hours, arriving at 6 a.m. of the eighth. This makes a total of 160 hours, or six days and 16 hours. Vessels bound through the Yucatan Channel should leave the convoy about one hundred miles from Tortugas. At Key West the escorting vessel will have a period of 36 hours for coaling. At the expiration of this period, or exactly 8 days and 4 hours since leaving Tampico, the return convoy could start at 6 p.m. of the ninth. The convoy would arrive at Tampico at 10 a.m. of the sixteenth. At Tampico the escorting vessel would have 28 hours before starting on another trip. The escorting vessel should report by radio the probable time the convoy will arrive at Heald Rock and at Mouth of Mississippi, so that vessels to join the convoy at these places can be there to join the convoy promptly. It will be noted that convoys arrive and leave all stopping places during daylight. . . .

Four naval vessels will be sufficient for this escort system.

     In comparing the two escort systems it will be noted that the first requires nine days for vessels to go from Tampico to Key West, considerable time being wasted by the fact that the three convoys are exceedingly difficult to coordinate and therefore there must be delays at Galveston and the mouth of the Mississippi. This system has the advantage however that not so much cruising for the escorting vessels is required and that all coaling can be done in United States ports.

     The second system has the advantage that only seven days are required for the trip from Tampico to Key West and that, as the same escort makes the entire trip, the arrangements for the convoy will be simpler than if three escorts were used and separate convoys had to be made up. This system, however, has the disadvantage that longer distances will be steamed by the escorts and that all will have to coal in Mexican waters, unless a stop is made at Galveston for this purpose. The convoy passes through District Waters between Galveston and the Mouth of the Mississippi. It will be advantageous to leave the convoy during this part of the route under command of the American Patrol Detachment.

     It is decided that the second escort system is the more efficient.

     Considering all three courses of action regarding unarmed merchant vessels it is decided to use the second escort system. All preparations for putting it into effect on short notice should be made at once. Although it is impracticable to make a definite decision at this time as to what vessels should be used for escort, the following are considered the best suited for this duty: Cincinnati, Yorktown, Anniston and Petrel. After the Annapolis has been repaired, she will be available as a reserve escort.

     As the number of unarmed merchant vessels in the convoys between Mouth of the Mississippi would probably reach 25 or 30, the escort of one naval vessel would be sufficient to give protection only against submarines operating on the surface. Therefore the convoy system between Mouth of the Mississippi and Key West should be supplemented by the sending of unarmed vessels under the escort of heavily armed merchant vessels, whenever this can be done. This measure will also increase the rapidity of the flow of shipping, as vessels will not be required to wait for the formation of the convoy. The same measure could be used to lesser extent for vessels sailing from Galveston and Port Arthur to the Eastward.

     Attention is called to the fact that the tactical hunting unit at Tampico should be able to keep submarines clear while the convoy is assembling there. Then the convoy will be able to keep within the 10 fathom curve as far as the Mouth of the Mississippi. Along this run they will be in practically no danger of torpedo attack, while the escort will be able to beat off a gunfire attack. At the Mouth of the Mississippi the tactical hunting group there should be able to drive clear all submarines from the position in which the convoy is being reorganized, and should be able to operate effectively against enemy submarines working in the area to the Southeastward of the Mouth of the Mississippi, thus incidently affording protection to the convoy as it proceeds toward the Florida Straits. As the two tactical hunting units based on Tortugas will cover the area to the Westward and Northward of that place the convoy will be incidently furnished with this support when approaching the Straits. It will thus be seen that the escort system works in perfectly with the operations of the Hunting groups.

     The remaining vessels of the Detachment---Ozark,Albatross,Eagle, and Dorothea should be used in Mexican Waters. Ozark should be based at Tampico until arrangements can be made for her relief by another monitor. Dorothea and Eagle could be used off Tampico, Taxpam and Tamishua, escorting merchant vessels approaching or leaving ports, patrolling the pipe lines and sweeping for mines. One pair of mine sweepers should be used in Mexican Waters.

     The Campeche Bank and the Mexican Coast from Vera Cruz to Cape Catoche affords the enemy excellent opportunities for submarine bases. Sailing vessels with oil and provisions could easily leave Mexican Ports in this region and meet a submarine in an appointed rendezvous. The anchorages in Alacran Reef, Arenas Cay and Arcas Cay must be watched with special care. Albatross is excellently fitted for patrolling this region and Dorothea and Eagle might be used if necessary.

     Two sailing vessels could be used as decoys and sent through the area in which the enemy is operating, accompanied by K-7 and K-8. . . .

DECISION.

     I. When submarines are definitely located in or actually approaching the Gulf of Mexico, the following measures should be carried out:10

1.Western Patrol, Captain S. V. Graham.11

(a) Salem and three Submarine Chasers, with such others as may be added from the Eighth Naval District, to base on Lobos Island for use as a hunting group.

(b) Ozark to be station ship at Tampico.

(c) Albatross to search Mexican Coast between Vera Cruz and Cape Catoche and the Campeche Bank.

(d) Dorothea and Eagle to be used at the discretion of the Commander Western patrol.

2.Northern Patrol, Commanding Officer Raleigh.12

Raleigh and three submarine chasers to act as a hunting group based on the Mouth of the Mississippi. <ok>

3.Eastern Patrol

Dolphin, Marblehead and six submarine chasers to act as a hunting group, based on Tortugas and Key West. <ok>

4.Convoy Escorts

Cincinnati, Anniston, Yorktown and Petrel to escort <unarmed> convoys between Tampico and Key West via Heald Rock (off Galveston) and Mouth of the Mississippi at four day intervals. Annapolis to be a reserve escort after repairs are completed.

5.To supplement the escort system and reduce the size of convoys, and consequent delays, to use heavily armed merchant vessels as convoy escorts to unarmed vessels from Galveston, Port Arthur and the Mouth of the Mississippi River to Key West and return. The convoys from Galveston and Port Arthur to hug the coast, keeping within the ten fathom line, until off the mouth of the Mississippi.

6.To use two colliers, carrying both coal and gasoline; one to be at either Tampico or Lobos Island; the other en route to or from Hampton Roads to relieve the first; surplus of coal to be deposited at Key West.

One coal and one gasoline barge to be at the Mouth of the Mississippi for use of the Northern Patrol.

7.To employ the Mobile Force of the Cuban Navy in Yucatan Channel, Gulf of Guacanaibebe, Bahamas, and Windward Passage in case submarines operate in these localities.

8.To fit out two sailing vessels as decoys and send them into the area in which the enemy is operating, escorted by our submarines K-7 and K-8.

II.  Until submarines are actually operating in or approaching the Gulf to assemble the greater part of the American Patrol Detachment at Key West, to carry out maneuvers in which the hunting groups actually search for submarines, to hold target practice for all vessels of the Detachment and to give them a course of the most intensive training in all anti-submarine operations.

E.A.Anderson