year 1917 was two-fold; _offensive_ in the direction of anti-submarine
measures (this was partly the business of the Anti-Submarine Division of
the Naval Staff and partly that of the Operations Division); _defensive_
in the direction of protective measures for trade, whether carried in
our own ships or in ships belonging to our Allies or to neutrals, this
being the business of the Trade and Mercantile Movements Divisions.

Prior to the formation of the Mercantile Movements Division the whole
direction of trade was in the hands of the Trade Division of the Staff.

The difficulty with which we were constantly faced in the early part of
1917, when the effective means of fighting the submarine were very
largely confined to the employment of surface vessels, was that of
providing a sufficient number of such vessels for _offensive_ operations
without incurring too heavy risks for our trade by the withdrawal of
vessels engaged in what might be termed _defensive_ work. There was
always great doubt whether any particular offensive operation undertaken
by small craft would produce any result, particularly as the numbers
necessary for success were not available, whilst there was the practical
_certainty_ that withdrawal of defensive vessels would increase our
losses; the situation was so serious in the spring of 1917 that we could
not carry out experiments involving grave risk of considerably increased
losses.

On the other hand, the sinking of one enemy submarine meant the possible
saving of a considerable number of merchant ships. It was difficult to
draw the line between the two classes of operations.

The desire of the Anti-Submarine Division to obtain destroyers for
offensive use in hunting flotillas in the North Sea and English Channel
led to continual requests being made to me to provide vessels for the
purpose. I was, of course, anxious to institute offensive operations,
but in the early days of 1917 we could not rely much on depth-charge
attack, owing to our small stock of these charges, and my experience in
the Grand Fleet had convinced me that for success in the alternative of
hunting submarines for a period which would exhaust their batteries and
so force them to come to the surface, a large number of destroyers was
required, unless the destroyers were provided with some apparatus which
would, by sound or otherwise, locate the submarine. This will be
realized when the fact is recalled that a German submarine could remain
submerged at slow speed for a period which would enable her to travel a
distance of some 80 miles. As this distance could be covered in any
direction in open waters such as the North Sea, it is obvious that only
a very numerous force of destroyers steaming at high speed could cover
the great area in which the submarine might come to the surface. She
would, naturally, select the dark hours for emergence, as being the
period of very limited range of vision for those searching for her. In
confined waters such as those in the eastern portion of the English
Channel the problem became simpler. Requests for destroyers constantly
came from every quarter, such as the Commanders-in-Chief at Portsmouth
and Devonport, the Senior Naval Officer at Gibraltar, the Vice-Admiral,
Dover, the Rear-Admiral Commanding East Coast, and the Admiral at
Queenstown. The vessels they wanted did not, however, exist.

Eventually, with great difficulty, a force of six destroyers was
collected from various sources in the spring of 1917, and used in the
Channel solely for hunting submarines; this number was really quite
inadequate, and it was not long before they had to be taken for convoy
work.

Evidence of the difficulty of successfully hunting submarines was often
furnished by the experiences of our own vessels of this type, sometimes
when hunted by the enemy, sometimes when hunted in error by our own
craft. Many of our submarines went through some decidedly unpleasant
experiences at the hands of our own surface vessels and occasionally at
the hands of vessels belonging to our Allies. On several such occasions
the submarine was frequently reported as having been sunk, whereas she
had escaped.

As an example of a submarine that succeeded not only in evading
destruction, but in getting at least even with the enemy, the case of
one of our vessels of the "E" class, on patrol in the Heligoland Bight,
may be cited. This submarine ran into a heavy anti-submarine net, and
was dragged, nose first, to the bottom. After half an hour's effort,
during which bombs were exploding in her vicinity, the submarine was
brought to the surface by her own crew by the discharge of a great deal
of water from her forward ballast tanks. It was found, however, that the
net was still foul of her, and that a Zeppelin was overhead, evidently
attracted by the disturbance in the water due to the discharge of air
and water from the submarine. She went to the bottom again, and after
half an hour succeeded in getting clear of the net. Meanwhile the
Zeppelin had collected a force of trawlers and destroyers, and the
submarine was hunted for fourteen hours by this force, assisted by the
airship. During this period she succeeded in sinking one of the German
destroyers, and was eventually left unmolested.

For a correct appreciation of submarine warfare it is necessary to have
a clear idea of the characteristics and qualities of the submarine
herself, of the numbers possessed by the enemy, and of the rate at which
they were being produced. It is also necessary, in order to understand
the difficulty of introducing the counter measures adopted by the Royal
Navy, to know the length of time required to produce the vessels and the
weapons which were employed or which it was intended to employ in the
anti-submarine war.

The German submarines may be divided into four classes, viz.: Submarine
cruisers, U-boats, U.B.-boats, U.C.-boats. There were several variations
of each class.

The earlier _submarine cruisers_ of the "Deutschland" class were
double-hulled vessels, with a surface displacement of 1,850 tons, and
were about 215 feet long; they had a surface speed of about 12 knots and
a submerged speed of about 6 knots. They carried two 5.9-inch guns, two
22 pounders, two torpedo tubes, and 12 torpedoes. They could keep the
sea for quite four months without being dependent on a supply ship or
base.

The later _submarine cruisers_ were double-hulled, 275-320 feet long,
had a surface speed of 16-18 knots, and a submerged speed of about 7 to
8 knots. They carried either one or two 5.9-inch guns, six torpedo
tubes, and about 10 torpedoes. They had a very large radius of action,
viz., from 12,000 to 20,000 miles, at a speed of 6 knots. A large number
(some 30 to 40) of these boats were under construction at the time of
the Armistice, but very few had been completed.

There were two or three types of _U-boats_. The earlier vessels were 210
to 220 feet long, double-hulled, with a surface displacement of about
750 tons, a surface speed of 15 to 16 knots, and a submerged speed of
about 8 knots. They carried one or two 4.1-inch guns, four to six
torpedo tubes, and about 10 torpedoes.

Later vessels of the class were 230 to 240 feet long, and of 800 to 820
tons surface displacement, and carried six torpedo tubes and 16
torpedoes. Some of them, fitted as minelayers, carried 36 mines, and two
torpedo tubes, but only two torpedoes. A later and much larger class of
minelayers carried a 5.9-inch gun, four torpedo tubes, 42 mines, and a
larger number of torpedoes. The earlier _U-boats_ could keep the sea for
about five weeks without returning to a base or a supply ship; the later
_U-boats_ had much greater sea endurance.

The smaller _U.B.-boats_ were single-hulled, and about 100 feet long,
had a surface speed of 7 to 9 knots and a submerged speed of about 5
knots, and carried one 22-pounder gun, two torpedo tubes and four
torpedoes. These boats could keep the sea for about two weeks without
returning to a base or supply ship. A later class were double-hulled,
180 feet long, with greater endurance (8,000 miles at 6 knots), a
surface speed of 13 knots and a submerged speed of 8 knots; they carried
one 4.1-inch gun, five tubes and 10 torpedoes.

The earliest _U.C.-boats_ were 111 feet long, with a surface
displacement of 175 tons, a surface speed of 6-½ knots, and a submerged
speed of 5 knots. They carried 12 mines, but no torpedo tubes, and as
they had a fuel endurance of only 800 miles at 5-½ knots, they could
operate only in southern waters.

The later _U.C.-boats_ were 170 to 180 feet long, double-hulled, had a
surface speed of 11 to 12 knots and a submerged speed of about 7 knots,
carried 18 mines, three torpedo tubes, five torpedoes, and one
22-pounder gun, and their fuel endurance was 8,000 to 10,000 miles at a
speed of 7 to 8 knots.

At the end of February, 1917, it was estimated that the enemy had a
total of about 130 submarines of all types available for use in home
waters, and about 20 in the Mediterranean. Of this total an average of
between one-half and one-third was usually at sea. During the year about
eight submarines, on the average, were added monthly to this total. Of
this number some 50 per cent, were vessels of the mine-laying type.

All the German submarines were capable of prolonged endurance submerged.
The U-boats could travel under water at the slowest speed for some 48
hours, at about 4 knots for 20 hours, at 5 knots for about 12 hours, and
at 8 knots for about 2 hours.

They were tested to depths of at least 180 feet, but many submerged to
depths exceeding 250 feet without injury. They did not usually lie on
the bottom at depths greatly exceeding 20 fathoms (120 feet).

All German submarines, except possibly the _cruiser class_, could dive
from diving trim in from 30 seconds to one minute. The _U.B. class_ had
particularly rapid diving qualities, and were very popular boats with
the German submarine officers. Perhaps the most noticeable features of
the German submarines as a whole were their excellent engines and their
great strength of construction.

Prior to the month of February, 1917, it was the usual practice of the
enemy submarine in the warfare against merchant ships to give some
warning before delivering her attack. This was by no means a universal
rule, particularly in the case of British merchant vessels, as is
evidenced by the attacks on the _Lusitania, Arabic_, and scores of other
ships.

In the years 1915 and 1916, however, only 21 and 29 per cent.
respectively of the British merchant ships sunk by enemy submarines were
destroyed without warning, whilst during the first four months of the
unrestricted submarine warfare in 1917 the figure rose to 64 per cent.,
and went higher and higher as the months progressed.

Prior to February, 1917, the more general method of attack on ships was
to "bring them to" by means of gun-fire; they were then sunk by
gun-fire, torpedo, or bomb. This practice necessitated the submarine
being on the surface, and so gave a merchant ship defensively armed a
chance of replying to the gun-fire and of escaping, and it also gave
armed decoy ships a good opportunity of successful action if the
submarine could be induced to close to very short range.

The form of attack on commerce known as "unrestricted submarine warfare"
was commenced by Germany with the object of forcing Great Britain to
make peace by cutting off her supplies of food and raw material. It has
been acknowledged by Germans in high positions that the German Admiralty
considered that this form of warfare would achieve its object in a
comparatively short time, in fact in a matter of some five or six
months.

Experienced British naval officers, aware of the extent of the German
submarine building programme, and above all aware of the shadowy nature
of our existing means of defence against such a form of warfare, had
every reason to hold the view that the danger was great and that the
Allies were faced with a situation, fraught with the very gravest
possibilities.

The principal doubt was as to the ability of the enemy to train
submarine crews with sufficient rapidity to keep pace with his building
programme.

However, it was ascertained that the Germans had evidently devoted a
very great number of their submarines to training work during the period
September, 1915, to March, 1916, possibly in anticipation of the
unrestricted warfare, since none of their larger boats was operating in
our waters between these months; this fact had a considerable bearing on
the problem.

As events turned out it would appear either that the training given was
insufficient or that the German submarine officer was lacking in
enterprise.

There is no doubt whatever that had the German craft engaged in the
unrestricted submarine warfare been manned by British officers and men,
adopting German methods, there would have been but few Allied or neutral
merchant ships left afloat by the end of 1917.

So long as the majority of the German submarine attacks upon shipping
were made by gun-fire, the method of defence was comparatively simple,
in that it merely involved the supply to merchant ships of guns of
sufficient power to prevent the submarine engaging at ranges at which
the fire could not be returned. Whilst the _method_ of defence was
apparent, the problem of _supplying_ suitable guns in sufficient numbers
was a very different matter. It involved arming all our merchant ships
with guns of 4-inch calibre and above. In January, 1917, only some 1,400
British ships had been so armed since the outbreak of war.

It will be seen, therefore, that so long as ships sailed singly, very
extensive supplies of guns were required to meet gun attack, and as
there was most pressing need for the supply of guns for the Army in
France, as well as for the anti-aircraft defence of London, the prospect
of arming merchant ships adequately was not promising.

When the enemy commenced unrestricted submarine warfare attack by
gun-fire was gradually replaced by attack by torpedo, and the problem at
once became infinitely more complicated.

Gun-fire was no longer a protection, since the submarine was rarely
seen. The first intimation of her presence would be given by the track
of a torpedo coming towards the ship, and no defence was then possible
beyond an endeavour to manoeuvre the ship clear of the torpedo. Since,
however, a torpedo is always some distance ahead of the bubbles which
mark its track (the speed of the torpedo exceeding 30 knots an hour),
the track is not, as a rule, seen until the torpedo is fairly close to
the ship unless the sea is absolutely calm. The chance of a ship of low
speed avoiding a hit by a timely alteration of course after the torpedo
has been fired is but slight. Further, the only difficulty experienced
by a submarine in hitting a moving vessel by torpedo-fire, once she has
arrived in a position suitable for attack, lies in estimating correctly
the course and speed of the target. In the case of an ordinary cargo
ship there is little difficulty in guessing her speed, since it is
certain to be between 8 and 12 knots, and her course can be judged with
fair accuracy by the angle of her masts and funnel, or by the angle
presented by her bridge.

It will be seen, then, how easy was the problem before the German
submarine officers, and how very difficult was that set to our Navy and
our gallant Mercantile Marine.

It will not be out of place here to describe the methods which were in
force at the end of 1916 and during the first part of 1917 for affording
protection to merchant shipping approaching our coasts from the
direction of the Atlantic Ocean.

The general idea dating from the early months of the war was to disperse
trade on passage over wide tracts of ocean, in order to prevent the
successful attacks which could be so easily carried out if shipping
traversed one particular route. To carry out such a system it was
necessary to give each vessel a definite route which she should follow
from her port of departure to her port of arrival; unless this course
was adopted, successive ships would certainly be found to be following
identical, or practically identical, routes, thereby greatly increasing
the chance of attack. In the early years of the war masters of ships
were given approximate tracks, but when the unrestricted submarine
campaign came into being it became necessary to give exact routes.

The necessary orders were issued by officers stationed at various ports
at home and abroad who were designated Shipping Intelligence or
Reporting Officers. It was, of course, essential to preserve the secrecy
of the general principles governing the issue of route orders and of the
route orders themselves. For this reason each master was only informed
of the orders affecting his own ship, and was directed that such orders
should on no account fall into the hands of the enemy.

The route orders were compiled on certain principles, of which a few may
be mentioned:

(a) Certain definite positions of latitude and longitude were given
through which the ship was required to pass, and the orders were
discussed with the master of each vessel in order to ensure that they
were fully understood.

(b) Directions were given that certain localities in which submarines
were known to operate, such as the approaches to the coast of the United
Kingdom, were, if possible, to be crossed at night. It was pointed out
that when the speed of the ship did not admit of traversing the whole
danger area at night, the portion involving the greatest danger (which
was the inshore position) should, as a rule, be crossed during dark
hours.

(c) Similarly the orders stated that ships should, as a rule, leave port
so as to approach the dangerous area at dusk, and that they should make
the coast at about daylight, and should avoid, as far as possible, the
practice of making the land at points in general use in peace time.

(d) Orders were definite that ships were to zigzag both by day and at
night in certain areas, and if kept waiting outside a port.

(e) Masters were cautioned to hug the coast, as far as navigational
facilities admitted, when making coastal passages.

The orders (b), (c) and (d) were those in practice in the Grand Fleet
when circumstances permitted during my term in that command.

A typical route order from New York to Liverpool might be as follows:

"After passing Sandy Hook, hug the coast until dark, then make a good
offing before daylight and steer to pass through the following
positions, viz:

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 of _destroyers_ was 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.

Our _submarines_ were 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 destroyers _averaged_ about 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 (_Vide_ Chapter 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 using _Decoy 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 own _submarines_ offensively 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.

The _hydrophone_ had 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 the _mine_, 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.

A _new 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 of _depth 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.

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

Because of the time required for production, it was a sheer
impossibility to _put into effect_ any 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.




CHAPTER III

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 to _new 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