The submarine losses which are certain since outbreak of war are as given in attached cablegram.

It is estimated that between thirty and forty submarines operate at a time in the waters surrounding the British Islands and French Coast. At least one is now known to be on White Sea trade lanes.

29. _Best anti-submarine weapons_:

One of the most efficient weapons now used by all destroyers and patrol craft against submarines is the so-called "Depth Charge," sample and drawings of which have been forwarded by our Naval Attache. These are merely explosive charges designed to explode at a certain depth, formerly eighty feet, now about one hundred feet. They are dropped overboard where a submarine that has submerged is a.s.sumed to be and are counted upon to badly shake up and demoralize if they do not actually cause serious damage.

Howitzers and Bomb-throwers of large calibre are under construction, designed to throw similar depth charges to distances of about 2,000 yards. Details will be forwarded.

30. _Torpedo Protection_:

This subject may be summed up by the statement of the Captain of a British Dreadnought who said in effect that after a year's experience he did not fear being sunk by a torpedo. Unless struck by several the worst to be antic.i.p.ated is damage to shafts or rudder, thus necessitating towing. Cruisers have often been struck and been able to reach port.

Vital water-tight doors are kept continuously closed at sea.

Destroyer officers have been heard to express the curious opinion that the enemy ships were more or less unsinkable. This is probably to be explained by the fact that they carry very few supplies; that they have their storage s.p.a.ces compartmented or filled with wood or other water-excluding material; and that when in port, they quarter their crews in barracks, and when leaving for a cruise carry the minimum amount of berthing and supply facilities. These points, however, are not positively known.

On the contrary, all vessels of the British Fleet must be kept fully supplied and fuelled at all times for extended cruising. This is particularly true of Battle-cruisers and Cruisers.

31. All officers of rank and actual experience consulted are convinced that the enemy have no unusual methods of protection, or in fact any "surprises" in ordnance or other fighting equipment.

32. All are agreed that the best protection against torpedoes is SPEED and ZIGZAGGING.

33. It is a common experience of the Naval as well as Merchant service that torpedo wakes are reported where none exist. Many reports are received of torpedoes barely missing ships. This was true in the Jutland Battle. The Captain on one Battleship said that he received numerous reports of torpedoes pa.s.sing just ahead and just astern, nearly all of which he had reason to believe did not exist.

Streaks of suds, slicks, etc., are very deceiving and are easily mistaken for torpedo wakes, particularly when the danger of torpedoes is present. This accounts for many reports by pa.s.sengers on liners and other merchant craft of seeing many torpedoes just miss their mark.

34. _Submarine versus Submarine_:

There has always been opposition to using submarines against submarines, princ.i.p.ally on the grounds that the possibilities of their accomplishments would not be sufficiently great to justify the risk involved of mistaken ident.i.ty and resulting damage to friends.

The Director of Anti-Submarine Warfare believes, however, that such operations promise well, and the experiment is now being tried with as many submarines as can be spared from the Grand Fleet. Some enemy submarines have been destroyed by this method, usually torpedoed. One valuable feature of this method lies in the fact that as long as our submarines are not so used, the enemy submarine is always perfectly safe in a.s.suming that all submarines sighted are friends. If this certainty is removed the enemy will be forced to keep down more, and to take much greater precautions against detection. This is an advantage of no small account.

In addition to the possible offensive work that may be accomplished by our submarines on such duty, the plan furnishes us with more reliable information as to the limitations and capabilities of enemy vessels under the actual conditions existing in the areas in which they operate.

Without this knowledge based on actual experience too much is left to conjecture which is liable to lead to a great deal of misdirected effort.

(Signed) WM. S. SIMS.

APPENDIX IV

THE QUESTION OF ARMING MERCHANT SHIPS

To: Secretary of the Navy.

Through Admiralty. From Queenstown.

Sent: June 28, 1917.

Admiralty for Secretary Navy Washington, providing it meets Admiralty's full approval.

From Admiral Sims.

Referring to Department's opinion, reported in last two cables, to the effect that adequate armament and trained crews const.i.tute one of the most effective defensive anti-submarine measures, I again submit with all possible stress the following based on extended [Allied] war experience. The measures demanded, if enemy defeat in time is to be a.s.sured, are not defensive but offensive defensive. The merchantman's inherent weakness is lack of speed and protection. Guns are no defence against torpedo attack without warning, which is necessarily the enemy method of attack against armed ships. In this area alone during the last six weeks thirty armed ships were sunk by torpedoes without submarine being seen, although three of these were escorted each by a single destroyer. The result would of course have been the same no matter how many guns these ships carried or what their calibre. Three mystery ships, heavily manned by expert naval crews with much previous experience with submarine attack, have recently been torpedoed without warning. Another case within the month of mystery ship engaging submarine with gunfire at six thousand yards but submarine submerged and approached unseen and torpedoed ship at close range. The ineffectiveness of heaviest batteries against submarine attack is conclusively shown by Admiralty's practice always sending destroyers to escort their men-of-war. The comparative immunity of the relatively small number American ships, especially liners, is believed here to be due to the enemy's hopes that the pacifist movement will succeed. Cases are on record of submarines making successful gun attacks from advantageous sun position against armed ships without ship being able to see submarine.

I submit that if submarine campaign is to be defeated it must be by offensive measures. The enemy submarine mission must be destruction of shipping and avoidance of anti-submarine craft. Enemy submarines are now using for their final approach an auxiliary periscope less than two inches in diameter. This information just acquired. All of the experience in this submarine campaign to date demonstrates that it would be a seriously dangerous misapprehension to base our action on the a.s.sumption that any armament on merchantmen is any protection against submarines which are willing to use their torpedoes. The British have now definitely decided the adoption, to the maximum practicable extent, convoys from sixteen to twenty ships. This is an offensive measure against submarines, as the latter will be subject to the attack of our anti-submarine craft whenever they come within torpedoing distance of convoyed merchantmen. Moreover it permits of concentrated attack by our forces and obliges the enemy to disperse his forces to cover the various routes of approach.

Concerning Department's reference to a scheme for protection of merchant shipping which will not interfere with present escort duties, I submit that the time element alone prevents utilization of any new anti-submarine invention. The campaign may easily be lost before any such schemes can come into effective operation. The enemy is certainly counting on maximum effort being exerted before long nights and bad weather of autumn, that is, in next three months. Heaviest effort may be antic.i.p.ated in July and August. I again submit that protection of our coastlines and of Allied shipping must necessarily be carried out in field of enemy activity if it is to be effective. The mission of the Allies must be to force submarines to give battle. Hence no operations in home waters should take precedence over, or be allowed to diminish, the maximum effort we can exert in area in which enemy is operating, and must continue to operate in order to succeed.

SIMS.

APPENDIX V

THE ADVANTAGES OF THE CONVOY SYSTEM

LONDON, June 29, 1917.

From: Commander U.S. Naval Forces operating in European Waters.

To: Secretary of the Navy (Operations).

Subject: General report concerning military situation.

1. I feel that there is little to add to my recent cable despatches which, in view of the importance of the time element, have been made full and detailed.

2. To sum up my despatches briefly, I would repeat that I consider that the military situation is very grave indeed on account of the success of the enemy submarine campaign.

If the shipping losses continue as they have during the past four months, it is submitted that the Allies will be forced to dire straits indeed, if they will not actually be forced into an unsatisfactory peace.

The present rate of destruction is very much greater than the rate of building, and the shortage of tonnage is already so great that the efficiency of the naval forces is already reduced by lack of oil. Orders have just been given to use three-fifths speed, except in cases of emergency. This simply means that the enemy is winning the war.

3. My reasons for being so insistent in my cable despatches have been because of my conviction that measures of co-operation which we may take will be inefficient if they are not put into operation immediately, that is, within a month.

There is every reason to believe that the maximum enemy submarine effort will occur between now and the first of November, reaching its height probably during the latter part of July, if not earlier.

4. There is certainly no sovereign solution for the submarine menace except through well-established methods of warfare based upon fundamental military principles.

5. It is submitted that the cardinal military principle of concentration of effort is at present being pursued by the enemy and not by the Allies.

6. We are dispersing our forces while the enemy is concentrating his.

The enemy's submarine mission is and must continue to be the destruction of merchant shipping. The limitations of submarines and the distances over which they must operate prevent them from attacking our naval forces, that is, anti-submarine craft. They cannot afford to engage anti-submarine craft with guns; they must use torpedoes. If they should do so to any considerable extent their limited supply would greatly reduce their period of operation away from base, and the number of merchantmen they could destroy. Their object is to avoid contact with anti-submarine craft. This they can almost always do, as the submarine can see the surface craft at many times the distance the surface craft can see a periscope, particularly one less than two inches in diameter.

Moreover, the submarine greatly fears the anti-submarine craft because of the great danger of the depth charges. Our tactics should therefore be such as to force the submarine to incur this danger in order to get within range of merchantmen.