|
|
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
The _howitzer_ as 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 those
Date. actually issued. under proof.
July 24, 1917 35 48
October 1, 1917 92 167
December 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 ascertain _the most suitable type of
projectile_ amongst 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 earlier _smoke apparatus_ for 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 sets
July 3, 1917 - 2,563 sets
October 5, 1917 - 3,445 sets
November 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
output _per week_ of 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 and _might_
force 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
The _Hydrophone_, 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 the _direction_ of
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 the _direction_ of 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 1917 _directional_ hydrophones, 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 Launches_ were 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 Directional
Date General Service Mark I and Shark Fin Fish
1917. 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 four _shore hydrophone stations_ were 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" system_ of 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
The _defensive arming_ of 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 received _offensive_
armaments) 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 been
Date. provided for British Merchant
Ships excluding Howitzers.
January 1, 1917 1,420
April 1, 1917 2,181
July 1, 1917 3,001
October 1, 1917 3,763
January 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.
AIRCRAFT FOR ANTI-SUBMARINE WORK
_Anti-submarine work by aircraft_ was already in operation round our
coasts by the beginning of 1917, and during the year the increase in
numbers and improvement in types of machines rendered possible
considerable expansion of the work. Closer co-operation between surface
vessels and aircraft was also secured, and as the convoy system was
extended aircraft were used both for escort and observation work, as
well as for attack on submarines. For actual escort work airships were
superior to heavier-than-air machines owing to their greater radius of
action, whilst for offensive work against a submarine that had been
sighted the high speed of the seaplane or aeroplane was of great value.
In 1916 and the early part of 1917 we were but ill provided with
aircraft suitable for anti-submarine operations at any considerable
distance from the coast, and such aircraft as we possessed did not carry
sufficiently powerful bombs to be very effective in attacking
submarines, although they were of use in forcing these vessels to
submerge and occasionally in bringing our surface craft to the spot to
press home the attack.
The Royal Naval Air Service, under Commodore Godfrey Paine, devoted much
energy to the provision of suitable aircraft, and the anti-submarine
side of the Naval Staff co-operated in the matter of their organization;
with the advent of the large "America" type of seaplane and the
Handley-Page type of aeroplane, both of which carried heavy bombs,
successful attacks on enemy submarines became more frequent. They were
assisted by the airships, particularly those of the larger type.
Improvements which were effected in signalling arrangements between
ships and aircraft were instrumental in adding greatly to their
efficiency, and by the early summer of 1917 aircraft had commenced to
play an important part in the war against submarines and in the
protection of trade.
Thereafter progress became rapid, as the following figures show:
In June, 1917, aeroplanes and seaplanes patrolling for anti-submarine
operations covered 75,000 miles, sighted 17 submarines, and were able to
attack 7 of them.
In September, 1917, the distance covered by anti-submarine patrols of
aeroplanes and seaplanes was 91,000 miles, 25 submarines were sighted,
of which 18 were attacked.
In the four weeks ending December 8, 1917, in spite of the much shorter
days and the far less favourable flying weather experienced, the mileage
covered was again 91,000 miles; 17 submarines were sighted, of which 11
were attacked during this period.
As regards airships the figures again show the increased anti-submarine
work carried out:
In June, 1917, airships engaged in anti-submarine patrol covered 53,000
miles, sighted and attacked 1 submarine.
In September, 1917, they covered 83,000 miles, and sighted 8 submarines,
of which 5 were attacked.
In the four weeks ending December 8, 1917, they covered 50,000 miles,
sighted 6 submarines, and attacked 5 of them.
The airships were more affected by short days, and particularly by bad
weather, than the heavier than air craft, and the fact that they covered
practically the same mileage in the winter days of December as in the
summer days of June shows clearly the development that took place in the
interval.
During the whole of 1917 it was estimated that our heavier than air
craft sighted 135 submarines and attacked 85 of them, and our lighter
than air craft sighted 26 and attacked 15. The figures given in Chapter
IX of the number of submarines sunk during the war by aircraft (viz. 7
as a minimum), when compared with the number of attacks during 1917
alone suggest the difficulties of successful attack.
In September, 1917, as extensive a programme as was consistent with
manufacturing capabilities, in view of the enormous demands of the Army,
was drawn up by the Naval Staff for the development of aircraft for
anti-submarine operations during 1918.
The main developments were in machines of the large "America" type and
heavy bombing machines for attacking enemy bases, as well as other
anti-submarine machines and aircraft for use with the Grand Fleet.
Included in the anti-submarine operations of aircraft during 1917 were
the bombing attacks on Bruges, since the German submarines and the
shelters in which they took refuge were part of the objective.
These attacks were carried out from the aerodrome established by the
Royal Naval Air Service at Dunkirk. During 1917 the Naval Air Forces of
the Dover Command, which included the squadrons at Dunkirk, were under
the command of Captain C.L. Lambe, R.N., and the operations of this
force were of a very strenuous character and of the utmost value.
Bombing operations prior to the year of 1917 had been carried out by
various types of machines, but the introduction of the Handley-Page
aeroplanes in the spring of 1917 enabled a much greater weight of
bombs--viz. some 1,500 lbs.--to be carried than had hitherto been
possible. These machines were generally used for night bombing, and the
weight of bombs dropped on the enemy bases in Belgium rose with great
rapidity as machines of the Handley-Page type were delivered, as did the
number of nights on which attacks were made. It was no uncommon
occurrence during the autumn of 1917 for six to eight tons of bombs to
be dropped in one night. I have not the figures for 1918, but feel no
doubt that with the great increase in aircraft that became possible
during that year this performance was constantly exceeded.
SPECIAL SERVICE OR DECOY SHIPS
The story of the work of these vessels constitutes a record of
gallantry, endurance and discipline which has never been surpassed
afloat or ashore. The earliest vessels were fitted out during the year
1915 at Scapa, Rosyth, Queenstown and other ports, and from the very
first it was apparent that they would win for themselves a place in
history. The earliest success against an enemy submarine by one of these
vessels was achieved by the _Prince Charles_, fitted out at Scapa, and
commanded by Lieutenant Mark-Wardlaw, an officer on the Staff of Admiral
Sir Stanley Colville, then Admiral Commanding the Orkneys and Shetlands.
In the early months of 1917 it was decided to augment greatly the force
of these special service vessels, and steps were taken to organize a
separate Admiralty Department for the work. Special experience was
needed, both for the selection of suitable ships and for fitting them
out, and care was taken to select officers who had been personally
connected with the work during the war; the advice of successful
commanders of decoy ships was also utilized. At the head was Captain
Alexander Farrington, under whose directions several ships had been
fitted out at Scapa with great ingenuity and success. Every class of
ship was brought into the service: steam cargo vessels, trawlers,
drifters, sailing ships, ketches, and sloops specially designed to have
the appearance of cargo ships. These latter vessels were known as
"convoy sloops" to distinguish them from the ordinary sloop. Their
design, which was very clever, had been prepared in 1916 by Sir Eustace
T. D'Eyncourt, the Director of Naval Construction. The enemy submarine
commanders, however, became so wary owing to the successes of decoy
ships that they would not come to the surface until they had inspected
ships very closely in the submerged condition, and the fine lines of the
convoy sloops gave them away under close inspection.
In the early spring of 1917 the Director of Naval Construction was asked
whether the "P" class of patrol boats then under construction could be
altered to work as decoy vessels, as owing to their light draught they
would be almost immune from torpedo attack.
A very good design was produced, and some of the later patrol boats were
converted and called "P Q's." These vessels had the appearance of small
merchant ships at a cursory glance. They would not, however, stand close
examination owing, again, to their fine lines, but being better sea
boats than the "P's," by reason of their greater freeboard, the design
was continued, and they met with considerable success against submarines
(especially in the Irish Sea) by ramming and depth charge tactics, the
submarines when submerged probably not realizing when observing the "P
Q.'s" through a periscope the speed of which they were capable.
During 1917, when the unrestricted submarine warfare was in progress,
many of the decoy vessels were fitted with torpedo tubes, either above
water or submerged, since, as the submarine commanders became more wary,
they showed great dislike to coming to the surface sufficiently close to
merchant ships to admit of the gun armament being used with certainty of
success. A torpedo, on the other hand, could, of course, be used
effectively against a submarine whilst still submerged. The use also
became general of casks or cargoes of wood to give additional flotation
to decoy ships after being torpedoed, so as to prolong their life in
case the submarine should close near enough to allow of effective
gunfire.
Another ruse adopted was that of changing the disguise of a decoy ship
during the night, so that she could not be identified by a submarine
which had previously made an attack upon her. In all cases of disguise
or of changing disguise it was essential that the decoy ship should
assume the identity of some class of vessel likely to be met with in the
particular area in which she was working, and obviously the courses
steered were chosen with that object in view.
Again, since for success it was essential to induce the submarine to
come within close range so that the decoy ship's gunfire should be
immediately effective, it was necessary that her disguise should stand
the closest possible examination through the periscope of a submarine.
German submarine commanders, after a short experience of decoy ships,
were most careful not to bring their vessels to the surface in proximity
to craft that were apparently merchant ships until they had subjected
them to the sharpest scrutiny at short range through the periscope, and
the usual practice of an experienced submarine commander was to steer
round the ship, keeping submerged all the time.
Not only was it essential that there should be no sign of an armament in
the decoy ship, or a man-of-war-like appearance in any respect, but when
the "panic" signal was made to lead the submarine commander to think
that his attack had succeeded, precautions had to be taken against the
presence of more than the ordinary number of men in the boats lowered
and sent away with the supposed whole ship's company; also the sight of
any men left on board would at once betray the real character of the
decoy ship and result in the disappearance of the submarine and the
probable sinking of the disguised craft by torpedo fire.
During the late summer of 1917 it became evident that the submarine
commanders had become so suspicious of decoy craft that the chances of
success by the larger cargo vessels were not sufficient to justify any
further addition to existing numbers in view of the increasing shortage
of shipping; a considerable fleet of steamers building for this purpose
was therefore diverted to trade purposes. The number of smaller vessels,
particularly sailing craft, was, however, increased especially in
Mediterranean waters where they had not been previously operating on an
extensive scale.
|
