tly 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 fo

nts Division the whole direction of trade was i

ut 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

ossible saving of a considerable number of merchant ships. It was

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 submari

es in the spring of 1917, and used in the Channel solely for hunting submarines; this number

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 o

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

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

s, viz.: Submarine cruisers, U-boats, U.B.-boats, U.C

ut 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 p

rried 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,

ith a surface displacement of about 750 tons, a surface speed of 15 to 16 knots, and a submerged speed of

ers, 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 larg

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

of 6-? knots, and a submerged speed of 5 knots. They carried 12 mines, but no torpedo tubes, and as

s and a submerged speed of about 7 knots, carried 18 mines, three torpedo tubes, five torpedoes, an

ters, 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 abo

ats could travel under water at the slowest speed for some 48 hours, at about 4 k

to depths exceeding 250 feet without injury. They did not usually

. class had particularly rapid diving qualities, and were very popular boats with the German submarine officers. Perhaps the mo

t ships to give some warning before delivering her attack. This was by no means a universal rule, particularly in the

by enemy submarines were destroyed without warning, whilst during the first four months of the unrestricted

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

make peace by cutting off her supplies of food and raw material. It has been acknowledged by Germans in high positions that the German Admiral

of the shadowy nature of our existing means of defence against such a form of warfare, had every reason to hold the view

enemy to train submarine crews with sufficient

rk during the period September, 1915, to March, 1916, possibly in anticipation of the unrestricted warfare, since none of

the training given was insufficient or that the G

rine warfare been manned by British officers and men, adopting German methods, there w

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 numb

to meet gun attack, and as there was most pressing need for the supply of guns for the Army in France, as well

ack by gun-fire was gradually replaced by attack by torpedo

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,

he German submarine officers, and how very difficult was

the end of 1916 and during the first part of 1917 for affording protection to me

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 pract

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 re

ed on certain principles, of

which the ship was required to pass, and the orders were discussed with th

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 da

dangerous area at dusk, and that they should make the coast at about daylight, and should avo

zigzag both by day and at night in certain

oast, as far as navigational facilities

ractice in the Grand Fleet when circumstanc

rom New York to Liverpo

rk, then make a good offing before daylight and s

N. Long

N. Long

N. Long

30' N. Lo

uskar, up the Irish coast (inside the banks if possible), and across the Irish Channel during da

English coast from the south of Ireland, and

early part of 1917 as to approach the coast in four dif

c bound towards the western ap

ffic making for th

ffic making for th

g for the east coast of Engl

at the end of the book). They were changed occasionally when suspicion was aroused that

gational map of the waters southwest o

se. 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 bu

gational map of the waters southwest o

r 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 arrangem

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 dange

dge 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

rines being located in any particular position, and a continual change of the signals for this purpose was necessary to guard agains

peaking, 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 abo

f the instructions f

llowing round the bays, except when passing Torba

south of the Shambles and steer for Anvil Point

so

he instructions directed that ships were to leave the daylight route at dusk

part 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 wh

ollow when navigating to or from the Bristol C

neither the cruisers to marshal the convoy to the submarine ar

ge 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 Euro

ilst 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, t

e occupied in the production of small craft i

though shortly before the war efforts were made to reduce the time to something

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 f

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 o

ve months, and that of submarine cruisers at eighteen months. German submarine officers gav

e construction of the German submarines. It is not stated whether he had access to official figu

ship production attained by some firms in t

om 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 Comp

se of destroyers and other small surface craft. There were, of course, other methods

sible to increase the number of these ships at the cost of taking merchant ships

(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 surf

developed into an effective instrument for locating submarines, and although trials of the different patterns whi

ed, was the mine, if laid in sufficiently large numbers. Unfortunately, in Jan

ines was run against a number of our mines, with the result that only about 33 per cent. of the mines (fitted, of course,

h 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

n 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 mi

of destroyers, this system became in itself, to a certain extent, an offensive operation, since it necessarily forced the enemy submarines

pth charges, which was their principal anti-submarine weapon; as it became feasible to increase largely the supply of

the early days of the year 1917, i

ed, and neutral) from submarine and mine attack in the

ry -

ry - 5

- 55

- 87

- 58

- 6

bmarine 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 f

h were taken to deal with the problem, and the degr