CHAPTER III

Lat. 38° N. Long. 68° W.Lat. 41° N. Long. 48° W.Lat. 46° N. Long. 28° W.Lat. 51° 30' N. Long. 14° W.

"Thence make the coast near the Skelligs approximately at daylight, hug the Irish coast to the Tuskar, up the Irish coast (inside the banks if possible), and across the Irish Channel during dark hours. Thence hug the coast to your port; zigzag by day and night after passing, Long. 20° W."

Sometimes ships were directed to cross to the English coast from the south of Ireland, and to hug the English coast on their way north.

The traffic to the United Kingdom was so arranged in the early part of 1917 as to approach the coast in four different areas, which were known as Approach A, B, C, and D.

Approach A was used for traffic bound towards the western approach to the English Channel.

Approach B for traffic making for the south of Ireland.

Approach C for traffic making for the north of Ireland.

Approach D for traffic making for the east coast of England via the north of Scotland.

The approach areas in force during one particular period are shown on Chart A (in pocket at the end of the book). They were changed occasionally when suspicion was aroused that their limits were known to the enemy, or as submarine attack in an area became intense.

[Transcriber's note: Chart A is a navigational map of the waters southwest of England, with approach routes marked.]

The approach areas were patrolled at the time, so far as numbers admitted, by patrol craft (trawlers, torpedo-boat destroyers, and sloops), and ships with specially valuable cargoes were given directions to proceed to a certain rendezvous on the outskirts of the area, there to be met by a destroyer or sloop, if one was available for the purpose. The areas were necessarily of considerable length, by reason of the distance from the coast at which submarines operated, and of considerable width, owing to the necessity for a fairly wide dispersion of traffic throughout the area. Consequently, with the comparatively small number of patrol craft available, the protection afforded was but slight, and losses were correspondingly heavy. In the early spring of 1917, Captain H.W. Grant, of the Operations Division at the Admiralty, whose work in the Division was of great value, proposed a change in method by which the traffic should be brought along certain definite "lines" in each approach area. Typical lines are shown in Chart B.

[Transcriber's note: Chart B is a navigational map of the waters southwest of Ireland, with approach routes marked.]

The idea was that the traffic in, say, Approach Route B, should, commencing on a certain date, be ordered by the Routeing Officer to pass along the line Alpha. Traffic would continue along the line for a certain period, which was fixed at five days, when it would be automatically diverted to another line, say Gamma, but the traffic along Gamma would not commence until a period of 24 hours had elapsed since discontinuance of the use of the line Alpha. This was necessary in order to give time for the patrol craft to change from one line to the other. During this period of 24 hours the arrangement for routeing at the ports of departure ensured that no traffic would reach the outer end of any of the approach lines, and consequently that traffic would cease on line Alpha 24 hours before it commenced on line Gamma. After a further period of five days the line would again change automatically.

It was necessary that Shipping Intelligence Officers should have in their possession the orders for directing traffic on to the various lines for some considerable time ahead, and the masters of ships which were likely to be for some time at sea were informed of the dates between which the various lines were to be used, up to a date sufficient to cover the end of their voyage. There was, therefore, some danger of this information reaching the enemy if a vessel were captured by a submarine and the master failed to destroy his instructions in time. There was also some danger in giving the information to neutrals.

However, the system, which was adopted, did result in a reduction of losses during the comparatively short time that it was in use, and the knowledge that patrol craft on the line would be much closer together than they would be in an approach area certainly gave confidence to the personnel of the merchant ships, and those who had been forced to abandon their ship by taking to the boats were afforded a better chance of being picked up.

Various arrangements were in existence for effecting rapidly a diversion of shipping from one route to another in the event of submarines being located in any particular position, and a continual change of the signals for this purpose was necessary to guard against the possibility of the code being compromised by having fallen into enemy hands, an event which, unfortunately, was not infrequent.

Elaborate orders were necessary to regulate coastal traffic, and fresh directions were continually being issued as danger, especially danger from mines, was located. Generally speaking, the traffic in home waters was directed to hug the coast as closely as safe navigation permitted. Two reasons existed for this, (a) in water of a depth of less than about eight fathoms German submarines did not care to operate, and (b) under the procedure indicated danger from submarine attack was only likely on the side remote from the coast.

Here is an example of the instructions for passing up Channel:

From Falmouth to Portland Bill.—Hug the coast, following round the bays, except when passing Torbay. (Directions followed as to the procedure here.)

From Portland Bill to St. Catherines.—Pass close south of the Shambles and steer for Anvil Point, thence hug the coast, following round the bays.

And so on.

As it was not safe navigationally to follow round the bays during darkness, the instructions directed that ships were to leave the daylight route at dusk and to join the dark period route, showing dimmed bow lights whilst doing so.

Two "dark period routes" were laid down, one for vessels bound up Channel, and another for vessels bound down Channel, and these routes were some five miles apart in order to minimize the danger of collision, ships being directed not to use their navigation lights except for certain portions of the route, during which they crossed the route of transports and store ships bound between certain southern British ports (Portsmouth, Southampton and Devonport) and French ports.

Routes were similarly laid down for ships to follow when navigating to or from the Bristol Channel, and for ships navigating the Irish Sea.

Any system of convoy was at this time out of the question, as neither the cruisers to marshal the convoy to the submarine area, nor the destroyers to screen it when there, were available.

There was one very important factor in the situation, viz., the comparative rate at which the Germans could produce submarines and at which we could build vessels suitable for anti-submarine warfare and for defence of commerce. The varying estimates gave cause for grave anxiety. Our average output ofdestroyerswas four to five per month. Indeed, this is putting the figure high; and, of course, we suffered losses. The French and Italians were not producing any vessels of this type, whilst the Japanese were, in the early part of 1917, not able to spare any for work in European waters, although later in the year they lent twelve destroyers, which gave valuable assistance in the Mediterranean. The United States of America were not then in the war. Consequently measures for the defence of the Allied trade against the new menace depended on our own production.

Oursubmarineswere being produced at an average rate of about two per month only, and—apart from motor launches, which were only of use in the finest weather and near the coast—the only other vessels suitable for anti-submarine work that were building at the time, besides some sloops and P-boats, were trawlers, which, whilst useful for protection patrol, were too slow for most of the escort work or for offensive duties. The Germans' estimate of their own submarine production was about twelve per month, although this figure was never realized, the average being nearer eight. But each submarine was capable of sinking many merchant ships, thus necessitating the employment of a very large number of our destroyers; and therein lay the gravity of the situation, as we realized at the Admiralty early in 1917 that no effort of ours could increase the output of destroyers for at least fifteen months, the shortest time then taken to build a destroyer in this country.

And here it is interesting to compare the time occupied in the production of small craft in Great Britain and in Germany during the war.

In pre-war days we rarely built a destroyer in less than twenty-four months, although shortly before the war efforts were made to reduce the time to something like eighteen to twenty months. Submarines occupied two years in construction.

In starting the great building programme of destroyers and submarines at the end of 1914, Lord Fisher increased very largely the number of firms engaged in constructing vessels of both types. Hopes were held out of the construction both of destroyers and of submarines in about twelve months; but labour and other difficulties intervened, and although some firms did complete craft of both classes during 1915 in less than twelve months, by 1916 and 1917 destroyersaveragedabout eighteen months and submarines even longer for completion.

The Germans had always built their small craft rapidly, although their heavy ships were longer in construction than our own. Their destroyers were completed in a little over twelve months from the official date of order in pre-war days. During the early years of the war it would seem that they maintained this figure, and they succeeded in building their smaller submarines of the U.B. and U.C. types in some six to eight months, as U.B. and U.C. boats began to be delivered as early as April, 1915, and it is certain that they were not ordered before August, 1914.

The time taken by the Germans to build submarines of the U type was estimated by us at twelve months, and that of submarine cruisers at eighteen months. German submarine officers gave the time as eight to ten months for a U-boat and eighteen months for a submarine cruiser.

(It is to be observed that Captain Persius in a recent article gives a much longer period for the construction of the German submarines. It is not stated whether he had access to official figures, and his statement is not in agreement with the figures given by German submarine officers.)

It is of interest to note here the rate of ship production attained by some firms in the United States of America during the war.

As I mention later (VideChapter vi, p. 157), the Bethlehem Steel Company, under Mr. Schwab's guidance, produced ten submarines for us in five months from the date of the order. Mr. Schwab himself informed me that towards the end of the war he was turning out large destroyers in six weeks. The Ford Company, as is well known, produced submarine chasers of the "Eagle" type in even a shorter period, but these vessels were of special design and construction.

I have dealt so far with the question of anti-submarine measures involving only the use of destroyers and other small surface craft. There were, of course, other methods both in use and under consideration early in 1917 when we took stock of the situation.

For some time we had been usingDecoy vessels, and with some success; it was possible to increase the number of these ships at the cost of taking merchant ships off the trade routes or by building. A very considerable increase was arranged.

The use of our ownsubmarinesoffensively against enemy submarines had also been tried, and had met with occasional success, but our numbers were very limited (the total in December, 1916, fit for oversea or anti-submarine work was about forty). They were much needed for reconnaissance and offensive work against surface men-of-war in enemy waters, and only a few were at the time available for anti-submarine operations, and then only at the cost of other important services.

Thehydrophonehad been in the experimental stage and under trial for a considerable period, but it had not so far developed into an effective instrument for locating submarines, and although trials of the different patterns which had been devised were pushed forward with energy, many months elapsed before it became a practicable proposition.

One of the best offensive measures against the enemy submarines, it was realized, was themine, if laid in sufficiently large numbers. Unfortunately, in January, 1917, we did not possess a mine that was satisfactory against submarines.

Our deficiency in this respect was clearly shown in the course of some trials which I ordered, when one of our own submarines was run against a number of our mines, with the result that only about 33 per cent. of the mines (fitted, of course, only with small charges) exploded. The Germans were well aware that our mines were not very effective against submarines.

We possessed at the time mines of two patterns, and whilst proving unsatisfactory against submarines, they were also found to be somewhat unreliable when laid in minefields designed to catch surface vessels, owing to a defect in the mooring apparatus. This defect was remedied, but valuable time was lost whilst the necessary alterations were being carried out, and although we possessed in April, 1917, a stock of some 20,000 mines, only 1,500 of them were then fit for laying. The position, therefore, was that our mines were not a satisfactory anti-submarine weapon.

Anew pattern mine, which had been designed on the model of the German mine during Sir Henry Jackson's term of office as First Sea Lord in 1916, was experimented with at the commencement of 1917, and as soon as drawings could be prepared orders for upwards of 100,000 were placed in anticipation of its success. There were some initial difficulties before all the details were satisfactory, and, in spite of the greatest pressure on manufacturers, it was not until November, 1917, that mines of this pattern were being delivered in large numbers. The earliest minefields laid in the Heligoland Bight in September and October, 1917, with mines of the new pattern met with immediate success against enemy submarines, as did the minefields composed of the same type of mine, the laying of which commenced in November, 1917, in the Straits of Dover.

When it became possible to adopt the system of bringing merchant ships in convoys through the submarine zone under the escort of a screen of destroyers, this system became in itself, to a certain extent, an offensive operation, since it necessarily forced the enemy submarines desirous of obtaining results into positions in which they themselves were open to violent attack by depth charges dropped by destroyers.

During the greater part of the year 1917, however, it was only possible to supply destroyers with a small number ofdepth charges, which was their principal anti-submarine weapon; as it became feasible to increase largely the supply of these charges to destroyers, so the violence of the attack on the submarines increased, and their losses became heavier.

The position then, as it existed in the early days of the year 1917, is described in the foregoing remarks.

Theresultmeasured in loss of shipping (British, Allied, and neutral) from submarine and mine attack in the first half of the year was as follows in gross tonnage:

January - 324,016February - 500,573March - 555,991April - 870,359May - 589,754June - 675,154

Because of the time required for production, it was a sheer impossibility toput into effectany fresh devices that might be adopted for dealing with submarine warfare for many months, and all that could be done was to try new methods of approach to the coast and, as the number of small craft suitable for escort duty increased, to extend gradually the convoy system already in force to a certain extent for the French coal trade and the Scandinavian trade.

In the chapters which follow the further steps which were taken to deal with the problem, and the degree of success which attended them, will be described.

ANTI-SUBMARINE OPERATIONS

The previous chapters have dealt with the changes in organization carried out at the Admiralty during the year 1917 largely with the object of being able to deal more effectively with the submarine warfare against merchant ships. Mention has also been made of the submarine problem with which the Navy had to deal; particulars of the anti-submarine and other work carried out will now be examined.

A very large proportion of the successful anti-submarine devices brought into use during 1917, and continued throughout the year 1918, were the outcome of the work of the Anti-Submarine Division of the Naval Staff, and it is but just that the high value of this work should be recognized when the history of the war comes to be written by future historians. As has been stated in Chapter I, Rear-Admiral A.C. Duff, C.B., was the original head of the division, with Captain F.C. Dreyer, C.B., Commander Yeats Brown, and Commander Reginald Henderson as his immediate assistants. Captain H.T. Walwyn took the place of Captain Dreyer on March 1, 1917, when the latter officer became Director of Naval Ordnance. When Admiral Duff was appointed Assistant Chief of the Naval Staff, with a seat on the Board, in May, 1917, Captain W.W. Fisher, C.B., became head of the division, which still remained one of the divisions of the Staff working immediately under the A.C.N.S. It is to these officers, with their most zealous, clever and efficient staff, that the institution of many of the successful anti-submarine measures is largely due. They were indefatigable in their search for new methods and in working out and perfecting fresh schemes, and they kept their minds open tonew ideas. They received much valuable assistance from the great civilian scientists who gave such ready help during the war, the function of the naval officers working with the scientists being to see that the effort was being directed along practical lines. They were also greatly indebted to Captain Ryan, R.N., for the exceedingly valuable work carried out by him at the experimental establishment at Hawkcraig. Many brilliant ideas were due to Captain Ryan's clever brain.

I doubt whether the debt due to Admiral Duff and Captain Fisher and their staff for their great work can ever be thoroughly appreciated, but it is certainly my duty to mention it here since I am better able to speak of it than any other person. In saying this I do not wish to detract in the least from the value of the part performed by those to whose lot it fell to put the actual schemes into operation. Without them, of course, nothing could have been accomplished.

When the Anti-Submarine Division started in December, 1916, the earlier devices to which attention was devoted were:

(1) The design and manufacture of howitzers firing shell fitted to explode some 40 to 60 feet under water with which to attack submarines when submerged.

(2) The introduction of a more suitable projectile for use against submarines than that supplied at the time to the guns of destroyers and patrol craft.

(3) The improvement of and great increase in the supply of smoke apparatus for the screening of merchant ships from submarines attacking by gunfire.

(4) A great increase in the number of depth charges supplied to destroyers and other small craft.

(5) The development of the hydrophone for anti-submarine work, both from ships and from shore stations.

(6) The introduction of the "Otter" for the protection of merchant ships against mines.

(7) A very great improvement in the rapidity of arming merchant ships defensively.

(8) The extended and organized use of air craft for anti-submarine work.

(9) A great development of the special service or decoy ship.

(10) The introduction of a form of net protection for merchant ships against torpedo fire.

Other devices followed, many of which were the outcome of work in other Admiralty Departments, particularly the Departments of the Director of Naval Ordnance and the Director of Torpedoes and Mines, working in conjunction with the Anti-Submarine or the Operations Division of the Naval Staff. Some of the new features were the development of depth-charge throwers, the manufacture and use of fast coastal motor-boats for anti-submarine work, the production of mines of an improved type for use especially against submarines, very considerable developments in the use of minefields, especially deep minefields, including persistent mining in the Heligoland Bight and the laying of a complete minefield at varying depths in the Straits of Dover; also, after the United States entered the war, the laying of a very extensive minefield right across the northern part of the North Sea. The provision of "flares" for illuminating minefields at night, and a system of submarine detection by the use of electrical apparatus were also matters which were taken up and pressed forward during 1917. During the year the system of dazzle painting for merchant ships was brought into general use.

On the operational side of the Naval Staff the work of dealing with enemy submarines before they passed out of the North Sea was taken in hand by organized hunting operations by destroyers and other patrol craft, and by the more extended use offensively of our own submarines, as vessels became available.

Considerable developments were effected in the matter of the control of mercantile traffic, and much was done to train the personnel of the mercantile marine in matters relating to submarine warfare.

Taking these subjects in detail, it will be of interest to examine the progress made during the year.

HOWITZERS

Thehowitzeras a weapon for use against the submarine when submerged was almost non-existent at the beginning of 1917, only thirty bomb-throwers, on the lines of trench-mortars, being on order. By April of that year designs for seven different kinds of bomb-throwers and howitzers had been prepared and approved, and orders placed for 1,006 weapons, of which number the first 41 were due for delivery in May. By the end of May the number of bomb-throwers and howitzers on order had been increased to 2,056, of eight different patterns. Over 1,000 of these weapons fired a bomb or shell carrying a burster exceeding 90 lbs. in weight, and with a range varying between 1,200 and 2,600 yards. Later in the war, as we gained experience of the value of this form of attack, heavier bombs were introduced for use in the existing bomb-throwers and howitzers. The howitzer as an anti-submarine weapon was handicapped by the comparatively small weight of the bursting charge of its shell. This applied more particularly to the earlier patterns, and to inflict fatal injury it was necessary to burst the shell in close proximity to the submerged submarine. This weapon, although not very popular at first, soon, however, proved its value, when employed both from patrol craft and from merchant ships.

One curious instance occurred on March 28, 1918, of a merchant ship being saved by a 7.5-inch howitzer. A torpedo was seen approaching at a distance of some 600 yards, and it appeared certain to hit the ship. A projectile fired from the howitzer exploded under water close to the torpedo, deflected it from its course, and caused it to come to the surface some 60 yards from the ship; a second projectile caused it to stop, and apparently damaged the torpedo, which when picked up by an escorting vessel was found to be minus its head.

Delivery of howitzers commenced in June, 1917, and continued as follows:

Total completed,No. of Howitzers including thoseDate. actually issued. under proof.July 24, 1917 35 48October 1, 1917 92 167December 10, 1917 377 422

The slow rate of delivery, in spite of constant pressure, which is shown by these figures gives some idea of the time required to bring new devices into existence.

PROJECTILE FOR USE AGAINST SUBMARINES

In January, 1917, the Director of Naval Ordnance was requested by the Anti-Submarine Division of the Naval Staff to carry out trials against a target representing the hull of a German submarine, so far as the details were known to us, to ascertainthe most suitable type of projectileamongst those then in existence for the attack of submarines by guns of 4.7-inch calibre and below.

The results were published to the Fleet in March, 1917. They afforded some useful knowledge and demonstrated the ineffectiveness of some of the shells and fuses commonly in use against submarines from 12-pounder guns, the weapon with which so many of our patrol craft were armed. The target at which the shell was fired did not, however, fully represent a German submarine under the conditions of service. The trials were therefore continued, and as a result, in June, 1917, a further order was issued to the Fleet, giving directions as to the type of projectile to be used against submarines from all natures of guns, pending the introduction of delay action fuses for the smaller guns; this was the temporary solution of the difficulty until a new type of shell evolved from the experience gained at the trials could be produced and issued. The trials, which were exhaustive, were pressed forward vigorously and continuously throughout the year 1917, and meanwhile more accurate information as to the exact form of the hull and the thickness of the plating of German submarines became available. Early in 1918 the first supplies of the new fuses were ready for issue.

SMOKE APPARATUS

The earliersmoke apparatusfor supply to merchant ships was designed towards the end of 1916.

One description of smoke apparatus consisted of an arrangement for burning phosphorus at the stern of a ship; in other cases firework composition and other chemicals were used. A dense smoke cloud was thus formed, and, with the wind in a suitable direction, a vessel could hide her movements from an enemy submarine or other vessel, and thus screen herself from accurate shell fire.

In another form the apparatus was thrown overboard and formed a smoke cloud on the water.

The rate of supply of sets of the smoke apparatus to ships is shown by the following figures:

April 1, 1917 - 1,372 setsJuly 3, 1917 - 2,563 setsOctober 5, 1917 - 3,445 setsNovember 26, 1917 - 3,976 sets

DEPTH CHARGES

Depth charges, as supplied to ships in 1917, were of two patterns: one, Type D, contained a charge of 300 lb. of T.N.T., and the other, Type D*, carried 120 lb. of T.N.T. At the commencement of 1917 the allowance to ships was two of Type D and two of Type D*, and the supply was insufficient at that time to keep up the stock required to maintain on board four per destroyer, the number for which they were fitted, or to supply all trawlers and other patrol craft with their allowance. The great value of the depth charge as a weapon against submarines, and the large number that were required for successful attack, became apparent early in 1917, and the allowance was increased. Difficulty was experienced throughout the year in maintaining adequate stocks owing to the shortage of labour and the many demands on our industries made by the war, but the improvement is shown by the fact that while the average outputper weekof depth charges was only 140 in July, it had become over 500 by October, and that by the end of December it was raised to over 800, and was still increasing very rapidly. As a consequence, early in 1918 it was found possible to increase the supply very largely, as many as 30 to 40 per destroyer being carried.

Improvements in the details of depth charges were effected during 1917. One such improvement was the introduction of a pistol capable of firing at much greater depths than had been in use before. The result was that all vessels, whether fast or slow, could safely use the 300-lb. depth charge if set to a sufficient depth. This led to the abolition of the Type D* charges and the universal supply of Type D.

In spite of the difficulties of dropping depth charges so close to submarines as to damage them sufficiently to cause them to come to the surface, very good results were obtained from their use when destroyers carried enough to form, so to speak, a ring round the assumed position at which the submarine had dived. In order to encourage scientific attack on submarines, a system of depth charge "Battle Practice" was introduced towards the end of 1917.

It is as well to correct a common misapprehension as to the value of depth charges in destroying submarines.

Many people held very exaggerated ideas on this subject, even to the extent of supposing that a depth charge would destroy a submarine if dropped within several hundred yards of her. This is, unfortunately, very far indeed from being the case; it is, on the contrary, necessary to explode the charge near the submarine in order to effect destruction. Taking the depth charge with 300 lb. weight of explosive, ordinarily supplied to destroyers in 1917, it was necessary to explode it within fourteen feet of a submarine to ensure destruction; at distances up to about twenty-eight feet from the hull the depth charge might be expected to disable a submarine to the extent of forcing her to the surface, when she could be sunk by gun-fire or rammed, and at distances up to sixty feet the moral effect on the crew would be considerable andmightforce the submarine to the surface.

A consideration of these figures will show that it was necessary for a vessel attacking a submarine with depth charges to drop them in very close proximity, and the first obvious difficulty was to ascertain the position of a submarine that had dived and was out of sight.

Unless, therefore, the attacking vessel was fairly close to the submarine at the moment of the latter diving there was but little chance of the attack being successful.

HYDROPHONES

TheHydrophone, for use in locating submerged submarines, although first evolved in 1915, was in its infancy, so far as supply to ships was concerned, at the commencement of 1917. Experiments were being carried out by the Board of Invention and Research at Harwich, and by Captain Ryan, R.N., at Hawkcraig, and although very useful results had been obtained and a considerable number of shore stations as well as some patrol vessels had been fitted with hydrophones, which had a listening range of one or two miles, all the devices for use afloat suffered from the disadvantage that it was not possible to use them whilst the ship carrying them was moving, since the noise of the vessel's own machinery and of the water passing along the side prevented the noise made by other vessels being located. What was required was a listening instrument that could be used by a ship moving at least at slow speed, otherwise the ship carrying the hydrophone was herself, when stopped, an easy target for the submarine's torpedo. It was also essential, before an attack could be delivered, to be able to locate thedirectionof the enemy submarine, and prior to 1917 all that these instruments showed was the presence of a submarine somewhere in the vicinity.

Much research and experimental work was carried out during the year 1917 under the encouragement and supervision of the Anti-Submarine Division of the Naval Staff. Two hydrophones were invented in the early part of 1917, one by Captain Ryan, R.N., and one by the Board of Invention and Research, which could be used from ships at very slow speed and which gave some indication of thedirectionof the sound; finally, in the summer of 1917, the ability and patience of one inventor, Mr. Nash, were rewarded, and an instrument was devised termed the "fish" hydrophone which to a considerable extent fulfilled the required conditions. Mr. Nash, whose invention had been considered but not adopted by the Board of Invention and Research before he brought it to the Anti-Submarine Division of the Naval Staff, laboured under many difficulties with the greatest energy and perseverance; various modifications in the design were effected until, in October, 1917, the instrument was pronounced satisfactory and supplies were put in hand.

The next step was to fit the "fish" hydrophone in certain auxiliary patrol vessels as well as some destroyers, "P" boats and motor launches, to enter and train men to work it, and finally to organize these vessels into "submarine hunting flotillas," drill them, and then set them to their task.

This work, which occupied some time, was carried out at Portland, where a regular establishment was set up for developing the "fish" hydrophone and for organizing and training the "hunting flotillas" in its use. A considerable amount of training in the use of the hydrophone was required before men became efficient, and only those with a very keen sense of hearing were suited to the work. The chances of the success of the hunting flotillas had been promising in the early experiments, and the fitting out of patrol craft and organizing and drilling them, proceeded as rapidly as the vessels could be obtained, but largely owing to the slow production of trawlers it was not until November that the first hunting flotilla fitted with the "fish" hydrophone was actually at work. The progress made after this date is illustrated by the fact that in December, 1917, a division of drifters, with a "P" boat, fitted with this "fish" hydrophone hunted an enemy submarine for seven hours during darkness, covering a distance of fifty miles, kept touch with her by sound throughout this period, and finished by dropping depth charges in apparently the correct position, since a strong smell of oil fuel resulted and nothing further could be heard of the submarine, although the drifters listened for several hours. On another occasion in the same month a division of drifters hunted a submarine for five hours. The number of hydrophones was increased as rapidly as possible until by the end of the year the system was in full operation within a limited area, and only required expansion to work, as was intended, on a large scale in the North Sea and the English Channel.

Meanwhile during 1917directionalhydrophones, which had been successfully produced both by Captain Ryan and by the Board of Invention and Research, had been fitted to patrol craft in large numbers, and "hunting flotillas" were operating in many areas. A good example of the working of one of these flotillas occurred off Dartmouth in the summer of 1918, when a division of motor launches fitted with the Mark II hydrophone, under the general guidance of a destroyer, carried out a successful attack on a German submarine. Early in the afternoon one of the motor launches dropped a depth charge on an oil patch, and shortly afterwards one of the hydrophones picked up the sound of an internal combustion engine; a line of depth charges was run on the bearing indicated by the hydrophone. The motor launches and the destroyer remained listening, until at about 6.0 P.M. a submarine came to the surface not far from Motor Launch No. 135, which fired two rounds at the submarine before the latter submerged. Other motor launches closed in, and depth charges were dropped by them in close proximity to the wash of the submarine. Oil came to the surface, and more depth charges were dropped in large numbers on the spot for the ensuing forty-eight hours. Eventually objects came to the surface clearly indicating the presence of a submarine. Further charges were dropped, and an obstruction on the bottom was located by means of a sweep. This engagement held peculiar interest for me, since during my visit to Canada in the winter of 1919 the honour fell to me of presenting to a Canadian—Lieutenant G.L. Cassady, R.N.V.R.—at Vancouver the Distinguished Service Cross awarded him by His Majesty for his work in Motor Launch No. 135 on this occasion.

Motor Launcheswere organized into submarine hunting flotillas during the year 1917. These vessels were equipped with the directional hydrophone as soon as its utility was established, and were supplied with depth charges. In the summer of 1917 four such hunting flotillas were busy in the Channel; the work of one of these I have described already, and they certainly contributed towards making the Channel an uneasy place for submarine operations.

These results were, of course, greatly improved on in 1918, as the numbers of ships fitted with the "fish" and other hydrophones increased and further experience was gained.

The progress in supply of hydrophones is shown by the following table:

Supply of DirectionalDate General Service Mark I and Shark Fin Fish1917. Portable Type. Mark II. Type. Type.Jul 31 2,750 500 - -Aug 31 2,750 700 - -Sep 30 2,750 850 - -Oct 31 3,500 1,000 - -Dec 31 3,680 1,950 870 37

HYDROPHONE STATIONS AND TRAINING SCHOOLS

At the beginning of 1917 fourshore hydrophone stationswere in use. During the year eight additional stations were completed and several more were nearing completion. The first step necessary was a considerable increase in the instructional facilities for training listeners both for the increased number of shore stations and for the large number of vessels that were fitted for hydrophone work during the year.

The greater part of this training took place at the establishment at Hawkcraig, near Rosyth, at which Captain Ryan, R.N., carried out so much exceedingly valuable work during the war. I am not able to give exact figures of the number of officers and men who were instructed in hydrophone work either at Hawkcraig or at other stations by instructors sent from Hawkcraig, but the total was certainly upwards of 1,000 officers and 2,000 men. In addition to this extensive instructional work the development of the whole system of detecting the presence of submarines by sound is very largely due to the work originally carried out at Hawkcraig by Captain Ryan.

The first hydrophone station which was established in the spring of 1915 was from Oxcars Lighthouse in the Firth of Forth; it was later in the year transferred to Inchcolm. Experimental work under Captain Ryan continued at Hawkcraig during 1915, and in 1916 a section of the Board of Invention and Research went to Hawkcraig to work in conjunction with him. This station produced the Mark II directional hydrophone of which large numbers were ordered in 1917 for use in patrol craft. It was a great improvement on any hydrophone instrument previously in use. Hawkcraig also produced the directional plates fitted to our submarines, as well as many other inventions used in detecting the presence of submarines.

In addition to the work at Hawkcraig an experimental station under the Board of Invention and Research was established near Harwich in January, 1917. The Mark I directional hydrophone was designed at this establishment in 1917, and other exceedingly valuable work was carried out there connected with the detection of submarines.

At Malta an experimental station, with a hydrophone training school, was started in the autumn of 1917, and good work was done both there and at a hydrophone station established to the southward of Otranto at about the same time, as well as at a hydrophone training school started at Gallipoli at the end of the year.

"OTTERS" AND PARAVANES

The "Otter" systemof defence of merchant ships against mines was devised by Lieutenant Dennis Burney, D.S.O., R.N. (a son of Admiral Sir Cecil Burney), and was on similar lines to his valuable invention for the protection of warships. The latter system had been introduced into the Grand Fleet in 1916, although for a long period considerable opposition existed against its general adoption, partly on account of the difficulties experienced in its early days of development, and partly owing to the extensive outlay involved in fitting all ships. However, this opposition was eventually overcome, and before the end of the war the system had very amply justified itself by saving a large number of warships from destruction by mines. It was computed that there were at least fifty cases during the war in which paravanes fitted to warships had cut the moorings of mines, thus possibly saving the ships. It must also be borne in mind that the cutting of the moorings of a mine and the bringing of it to the surface may disclose the presence of an hitherto unknown minefield, and thus save other ships.

Similarly, the "Otter" defence in its early stages was not introduced without opposition, but again all difficulties were overcome, and the rate of progress in its use is shown in the following statement giving the number of British merchant ships fitted with it at different periods of 1917:

By July 1, 95 ships had been fitted.By September 1, 294 ships had been fitted.By December 1, 900 ships had been fitted.

The system was also extended to foreign merchant ships, and supplies of "Otters" were sent abroad for this purpose.

A considerable number of merchant ships were known to have been saved from destruction by mine by the use of this system.

DEFENSIVE ARMING OF MERCHANT SHIPS

Thedefensive armingof merchant ships was a matter which was pressed forward with great energy and rapidity during the year 1917. The matter was taken up with the Cabinet immediately on the formation of the Board of Admiralty presided over by Sir Edward Carson, and arrangements made for obtaining a considerable number of guns from the War Office, from Japan, and from France, besides surrendering some guns from the secondary and anti-torpedo boat armament of our own men-of-war, principally those of the older type, pending the manufacture of large numbers of guns for the purpose. Orders for some 4,200 guns were placed by Captain Dreyer, the Director of Naval Ordnance, with our own gun makers in March, April and May, 1917, in addition to nearly 3,000 guns already on order for this purpose; 400 90-m.m. guns were obtained from France, the mountings being made in England. Special arrangements were also made by Captain Dreyer for the rapid manufacture of all guns, including the provision of the material and of extra manufacturing plant.

These orders for 4,200 guns and the orders for 2,026 howitzers placed at the same time brought the total number of guns and howitzers under manufacture in England for naval and merchant service purposes in May, 1917, up to the high figure of 10,761.

At the end of the year 1916 the total number of merchant ships that had been armed since the commencement of the war (excluding those which were working under the White Ensign and which had receivedoffensivearmaments) was 1,420. Of this number, 83 had been lost.

During the first six months of 1917 armaments were provided for an additional 1,581 ships, and during the last six months of that year a further total of 1,406 ships were provided with guns, an aggregate number of 2,987 ships being thus furnished with armaments during the year. This total was exclusive of howitzers.

The progress of the work is shown by the following figures:

Number or guns that had beenDate. provided for British MerchantShips excluding Howitzers.January 1, 1917 1,420April 1, 1917 2,181July 1, 1917 3,001October 1, 1917 3,763January 1, 1918 4,407

The figures given include the guns mounted in ships that were lost through enemy action or from marine risks.

It should be stated that the large majority of the guns manufactured during 1917 were 12-pounders or larger guns, as experience had shown that smaller weapons were usually outranged by those carried in submarines, and the projectiles of even the 12-pounder were smaller than was desirable. Of the 2,987 new guns mounted in merchant ships during the year 1917 only 190 were smaller than 12-pounders.

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