Naval History and Heritage Command

Commander Allen Buchanan to Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters

U. S. S. Downes.             

24 February 1918.       

FROM:     Commander, Allen Buchanan.

TO  :     Force Commander.

SUBJECT:  Hunting Division.

ESTIMATE OF THE SITUATION

MISSION

Discussion:-

The destruction of the Sms1 is without doubt the ultimate mission of the hunting division, however, the Sm must first be located, therefore is not the immediate Mission the search and location of the enemy

     In the District of the Irish Sea, there are the patrol positions of Kingstown, Holyhead, and Mersey. Each of these sections has attached a large force of Trawlers, drifters, minesweepers and motor launches. None of these craft can be called strong offensively; they lack both the speed and the armament. They are, however, equipped with hydrophones, and are og [i.e., of] greatest value as searchers, not only thru their equipment but also their number.

     The Vs2 are few in number and have speed and offensive power. As searchers they have the single advantage of speed, premitting them to cover a large area, but they are easily picked up by the Sm, and usuallybefore the V can see the Sm. Most instances of the Vs sighting Sms are more or less accidental; it was either due to the presence of a convoy as bait, compelling the Sm to show itself in order to attack, or it was due to visibility conditions being so low that the V stumbled on the Sm before the latter had chance to dive. The presence of the Sm is usually determined by the Merchant ship attacked, or by the patrol force either sighting or hearing a Sm.

     It would seem that the patrol force are more efficient as searchers than the Vs; these latter are the force of attack.

     It is axiomatic that the main force of attack must be kept concentrated, great superiority in power is essential to great success, it is only numbers that can annihilate, yet the foregoing hardly applies to the case in point, since the real power of any enemy likely to be encountered is small, and, if once definitely located probably can be well handled by the unit of the attacking force.

     The problem so far as the V is concerned is not one of concentrating attacking power to destroy a strong force, it is essentially one of locating the enemy, and the patrols with their equipment and numbers can do this more efficiently. It then becomes a question of coordinating the efforts of the searchers and the attackers.

     Searchers are too few, and to augment them with Vs is [not] that much help. Ont the other hand, the Vs, in searching, use up their fuel, material and personnel with but little return for the effort expended. Such expenditure detracts just so much from their usefulness when the necessity for attack comes. By this is not me[a]nt search in a well defined and probable area, but search at large in the hope of uncountering an enemy. Nor does attack mean the actual tactical contact, it means not only the real attack, but also the period of locating the enemy and placing the attacking force in position.

     It would seem that the entire operation might be better divided into three phases: (1) The search; (2) the approach; and three the attack.

     (1)  The search might be called the primary search: that search which is instituted and kept up constantly in likely locations to determine the presence of a Sm.

     (2)  The approach is a more limited search, a search in a definite area, to unable [i.e., enable] the attacking force to place themselves in a position for the attack.

     (3)  The attack is the final phase after the Sm is very closely located.

     If such is the case, it would seem that the immediate mission of the Vs begins with the second phase, and leads directly to the third. By employing them on the first phase is a blow in the dark, a wasted effort which depends more on good luck for success than anything else.

     In the above it must be borne in mind that it refers only to a limited number of Vs in a large area. If the time ever comes when there are sufficient Vs for the entire work, then not only can they be used in the primary search, but should be. In fact the case then becomes the second phase at once, and the immediate mission of the V remains the same.

     In any consideration of the use of a Hunting Division it must be borne in mind that, however, wrong is [i.e., in] principle it may be, that, due to the shortage of Vs, there is forced on all Vs something of the defensive. Ship’s must be protected as much as possible, and there is no better means of keeping the Sm submerged and making this problem difficult, than a number of fast Vs in the area constantly patrolling. This takes us back to the primary Search, and forces us to another compromise, but if we grant that our conclusions are sound, then we must restrict the use of the V’s of the Hunting Division to as little as possible of the primary Search or indefinite patrol.

M I S S I O N.

Destruction of enemy Sms.

Immediate Mission.

     Location of Enemy Sms after definite information.

Enemy’s Forces:-    Strength, Disposition and Probable Intentions:-

     Strength:- Whatever their strength may be, it must be acknowledged that their great strength is due to the nature of the weapon, rather than to the number. Such a strength as to require a great concentration of effort, the greater the number of vessels that can be brought to bear on one of the number of the enemy, the more chances of destroying that single unit. The numbers are required more in the approach than in the actual attack.

     Disposition:- From an examination of a chart showing sinking by and sightings of enemy Sms, it would seem that their disposition follows fairly well defined lines, shifting it may be from time to time. Sinkings well out in the Atlantic have been practically nil during the winter months. There have been an apparent concentration in the Irish Sea recently. These are general.

     The same applies to the more definite area of the Irish Sea. The Sm hunting ground is naturally where shipping concentrates, as off Mersey #1, his lurking ground is not so easily defined, but from ten days experience it is believed to be in the lees of the Irish Coast and the Isle of Man. It was first believed to be in the Lee of Ahglesia, also but that is not [i.e., now] doubted since this area is used to such an extent by the patrol force. Between Rockabill and Haulbowline, and between Haulbowline and St. John, a lee can usually be found with a suitable depth of water to lie at anchor on the bottom.

     Probable intentions: there can be no doubt but that a more or less concentrated effort is being made against the lines of communication in the Irish Sea, and that it will be continued may be expected. The Irish Sea affords a protected body of water with lines of communication limited well defined areas, and has many bays and sheltered nooks where the Sm can either lie on the bottom or come to the surface at night to recharge. Nor is it impossible that the Sm may receive some assistance from the shore in this locality.

     The Sm is not going to willing forego the above advantage.

     Own Forces:- Strength, Disposition and courses Open.

     Strength: Dealing now only with the Hunting Division the vessels should have the most recent equipment in oscillators and radio direction finders and armed with the maximum number of depth charges. Their strength must be used according to our mission for the destruction of enemy Sms, and their equipment, according to our immediate mission, for the location of the Sms within a small area. Their grate primary is their mobility, and to restrict that by installing apparatus requiring stopping, not only the ship but all auxiliaries,,is not only wrong in principle but a practicethat will soon lead to destruction of the machinery and consequently all mobility.

     Disposition:-  This division from Base Six3 can be best used at the southern entrance to the Irish Sea itself,and naturally against any attack on the south coast of Ireland. The Base is well located as such, but it should be supplemented by secondary bases if we keep in mind our mission, and not expend a large part of strength on useless search. For the southern entrance to the Irish Sea there are Waterford, Milford Haven and Wexford; from all these places there are working efficient patrols as the primary searchers. For the Irish Sea there are Kingstown, Holyhead and the Mersey, Kingstown and Holyhead are better as being more central and probable.

     Courses Open;- With 4 Vs and the employment of the secondary bases, it would seem possible to keep 3 at least at all times on duty in area. Three weeks away and one week at the main base for overhaul and boiler cleaning, including one day going to station and one to return.

     To remain away this length of time must necessarilym mean a liberal use of the secondary bases, not only for fuel and provisions, but for rest and recreation for the personnel. With great Sm activity there would be little chance for even this, but as things let up, one one boat could lay up for a day, refuel, give liberty and rest, while the others remained ready for instant service.

     Beyond this, if there is to be cooperation between the existing patrol force and the Hunting Vs, then there should be opportunity for them to get together, exchange ideas and discuss plans. To cooperate one must know the other’s limitations, powers and probable course of action.

     The so called approach, or search after rather definite information is the most difficult question. It is so easy for the Sm to dive and lie quiet, or run away at low speeds. No equipments a V be <can have> (live and) can quite meet these conditions, altho the most recent designs of oscillators will help. Motor launches capable of stopping everything and listening would be most valuable, they, working in conjunction with a V, on regular search curves would seem to give the greatest chance of success. The value of the V being in its greater mobility (        )4 and its greater power in the final attack.

     In the absence of M Ls.,5 the Vs equipped with oscillators are better than nothing. Commander Powell6 of the Parker has suggested two working together, alternating as listener while the other runs ahead. This keeps the Vs concentrated for the final attack, but covers only small possibilities of the Sm’s speeds. If the oscillator can be used with the ship making six or seven knots, occasionally stopping, it would seem better for them to run independent retiring search curves, or a retiring search patrol, which in itself covers lower speeds than those assumed. At all events, it is certain that such use of the Vs at least keeps the Sm submerged and bothers him, with always the chance of definitely locating him.

     Enemy submarines use the radio every night. Direction finders would be greatest help. Not only direction finders on the ships, but shore stations to locate the usual (the) night haunts, would be the greatest aid.

     The employment of kite balloons on V is doubtful value. They immediately give away the presence of your main force of attack, On the other hand, such balloons on drifters or trawlers would seem to improve these craft as searchers.

     The tactics of the attack as yet are in a very nebulous state. Consider first a single V fitted as is the Downes. The Downes carries 30 depth charges, two on chocks released hydraulically from the bridge, two Thornycroft depth charge throwers, and the remainder in three paralleled chutes, the dropping controlled by leavers worked at the atern, the signal for this last being a Klaxon horn mounted aft, with push button on the bridge. The following is the procedure planned:- AT blast on whistle, both charges on chocks set at I50’ are let go from the bridge, at same time both Thornycroft depth charge throwers are fired, these latter will be set at I00’ when the new American depth charges arrive. As these hit the water the Klaxon is sounded and twomore charges are tripped from the chutes set at 80’. This gives a pattern something like this all, charges going to. (This gives a pattern something like) simultaneous or I800 pounds of T. N. T.

     Either before or after this main attack, as many charges can be dropped from the chutes as is desired, the main attack to be delivered when believed tobe be directly over the Sm.

     If two or three Vs are working together, the leader should make the primary attack, and covered on each quarter at about I000 yards distance by the other Vs, who would let go when slightly beyond the position of the leaders attack, in order to cover a change of course of the Sm at the last minute.

     If working with MLs, the Vs should trail, stopping as the MLs, stop, and when the Sm is definitely located, advancing thru the line of M Ls and attacking as above.

Final.

     Experience may prove the above wrong, it will certainly improve it. It is only a beginning.7

Allen Buchanan.