ANTI-SUBMARINE TACTICS
In all warfare, new weapons of attack are, sooner or later, met by new
methods of defence. The submarine and the aeroplane are at present the
only weapons against which there is no true means of defence, and yet
one is being used as an antidote for the other without, however, any
very striking success so far. The seaplane may be able to distinguish
the dark patch in the sea caused by the hull of the submarine _in clear
water_, but she cannot destroy it, neither can she signal the _exact_
locality to an accompanying destroyer flotilla, owing to the speed with
which seaplane and submarine pass over and under each other;
furthermore, in rough weather or in shallow muddy water no sign of the
submarine when submerged is visible from above. The great value of the
seaplane as an antidote for submarines lies, however, first in the fact
that the water of the open sea is usually clear, and the _submarine
shadow_ is visible from above, and, secondly, in the great speed of
these aircraft which enables them to quickly cover miles of sea in their
search for hostile submarines and to report their presence in a given
locality by wireless to all ships operating within range.
When the enormous superficial area of a zone of war, such as the North
Sea and English Channel, is duly considered, however, the difficulty in
quickly and reliably locating from the air the few scattered “submarine
shadows” will be easily realized. To make this method of locating
submarines even fairly reliable an enormous fleet of seaplanes would be
required. Again seaplanes do not, in themselves, constitute a means of
defence against submarine attack, they merely increase the likelihood of
detection, but, in actual warfare, it has now been proved that for every
submarine detected by seaplanes two others pass quite unobserved.
Many means of attack on submarines have been proposed; and no doubt some
of these, in certain cases, would prove effective; but none can be
relied upon. Therefore, one of the points in favour of the submarine
still remains without its antidote. This is the _moral effect_; for if
there is no absolutely reliable means of defence, there can be no
feeling of security for surface warships or merchant vessels when
anywhere within the danger zone of the submarine.
Let us now examine briefly what practical methods of defence a modern
warship has against submarine attacks. Great speed is undoubtedly a
surface ship’s most reliable defence; and when combined with a frequent
change of course, would greatly reduce the chances of a successful
under-water attack. Should hostile submarines be on the line of advance
they would not know whether to wait and chance the enemy approaching
within torpedo range or whether to run to starboard or port. This is, if
the surface warship was steaming in an erratic course—not a zigzag
course, for then it might be possible to estimate, within torpedo range,
the position of the ship at a given point if the “tacks” were regular.
Should submarines be seen approaching, a surface vessel would do well to
turn her stern to the attacking flotilla, presenting as small a target
as possible, and deflecting the torpedoes by her propeller race.
The escape of the Battle Cruiser _Queen Mary_ and the Light Cruiser
_Lowestoft_, during the action in the Heligoland Bight, as described in
the dispatch of Vice-Admiral Sir David Beatty, K.C.B., demonstrates what
may be done by the skilful use of the helm on surface warships to
frustrate submarine attacks. So interesting, and informative as to the
actual fighting between British warships and hostile submarines, in this
dispatch that I give it here in full. It should, however, be studied in
conjunction with the comprehensive report—the first in the history of
Naval warfare detailing submarine attack and reconnaissance—from
Commodore Roger J. B. Keyes, C.B., of the British submarines, given on
page 28.
“H.M.S. _Lion_,
_1st September, 1914_.
“SIR,—I have the honour to report that on Thursday, 27th August, at 5
a.m., I proceeded with the First Battle Cruiser Squadron and First
Light Cruiser Squadron in company, to rendezvous with the
Rear-Admiral, _Invincible_.
“At 4 a.m., 28th August, the movements of the Flotillas commenced as
previously arranged, the Battle Cruiser Squadron and Light Cruiser
Squadron supporting. The Rear-Admiral, _Invincible_, with _New
Zealand_ and four Destroyers having joined my flag, the Squadron
passed through the pre-arranged rendezvous.
“At 8.10 a.m. I received a signal from the Commodore (T), informing me
that the Flotilla was in action with the enemy. This was presumably in
the vicinity of their pre-arranged rendezvous. From this time until 11
a.m. I remained about the vicinity ready to support as necessary,
intercepting various signals, which contained no information on which
I could act.
“At 11 a.m. the Squadron was attacked by three Submarines. The attack
was frustrated by rapid manœuvring and the four Destroyers were
ordered to attack them. Shortly after 11 a.m., various signals having
been received indicating that the Commodore (T) and Commodore (S) were
both in need of assistance, I ordered the Light Cruiser Squadron to
support the Torpedo Flotillas.
“Later I received a signal from the Commodore (T), stating that he was
being attacked by a large Cruiser, and a further signal informing me
that he was being hard pressed and asking for assistance. The Captain
(D), First Flotilla, also signalled that he was in need of help.
“From the foregoing the situation appeared to me critical. The
Flotillas had advanced only ten miles since 8 a.m., and were only
about twenty-five miles from two enemy bases on their flank and rear
respectively. Commodore Goodenough had detached two of his Light
Cruisers to assist some Destroyers earlier in the day, and these had
not yet rejoined. (They rejoined at 2.30 p.m.). As the reports
indicated the presence of many enemy ships—one a large Cruiser—I
considered that his force might not be strong enough to deal with the
situation sufficiently rapidly, so at 11.30 a.m. the Battle Cruisers
turned to E.S.E., and worked up to full speed. It was evident that to
be of any value the support must be overwhelming and carried out at
the highest speed possible.
“I had not lost sight of the risk of Submarines, and possible sortie
in force from the enemy’s base, especially in view of the mist to the
South-East.
“Our high speed, however, made submarine attack difficult, and the
smoothness of the sea made their detection comparatively easy. I
considered that we were powerful enough to deal with any sortie except
by a Battle Squadron, which was unlikely to come out in time, provided
our stroke was sufficiently rapid.
“At 12.15 p.m. _Fearless_ and First Flotilla were sighted retiring
West. At the same time the Light Cruiser Squadron was observed to be
engaging an enemy ship ahead. They appeared to have her beat.
“I then steered N.E. to sounds of firing ahead, and at 12.30 p.m.
sighted _Arethusa_ and Third Flotilla retiring to the Westward
engaging a Cruiser of the _Kolberg_ class on our Port Bow. I steered
to cut her off from Heligoland, and at 12.37 p.m. opened fire. At
12.42 the enemy turned to N.E., and we chased at 27 knots.
“At 12.56 p.m. sighted and engaged a two-funnelled Cruiser ahead.
_Lion_ fired two salvoes at her, which took effect, and she
disappeared into the mist, burning furiously and in a sinking
condition. In view of the mist and that she was steering at high speed
at right angles to _Lion_, who was herself steaming at 28 knots, the
_Lion’s_ firing was very creditable.
“Our Destroyers had reported the presence of floating mines to the
Eastward and I considered it inadvisable to pursue her. It was also
essential that the Squadrons should remain concentrated, and I
accordingly ordered a withdrawal. The Battle Cruisers turned North and
circled to port to complete the destruction of the vessel first
engaged. She was sighted again at 1.25 p.m. steaming S.E. with colours
still flying. _Lion_ opened fire with two turrets, and at 1.35 p.m.,
after receiving two salvoes, she sank.
“The four attached Destroyers were sent to pick up survivors, but I
deeply regret that they subsequently reported that they searched the
area but found none.
“At 1.40 p.m. the Battle Cruisers turned to the Northward, and _Queen
Mary_ was again attacked by a Submarine. The attack was avoided by the
use of the helm. _Lowestoft_ was also unsuccessfully attacked. The
Battle Cruisers covered the retirement until nightfall. By 6 p.m., the
retirement having been well executed and all Destroyers accounted for,
I altered course, spread the Light Cruisers, and swept northwards in
accordance with the Commander-in-Chief’s orders. At 7.45 p.m. I
detached _Liverpool_ to Rosyth with German prisoners, seven officers
and 79 men, survivors from _Mainz_. No further incident occurred.—I
have the honour to be, Sir, your obedient Servant.
“(Signed) DAVID BEATTY,
“Vice-Admiral.
“The Secretary of the Admiralty.”
Quick-firing guns of the 3-inch and 6-inch type are certainly the best
weapons for an attack on submarines. In combination with “sharp
look-outs,” they could be used with effect from the elevated positions
on the fore part of warships. The periscopic-tube of the submarine
always proves a target for gun-fire; but a grey steel tube, 3 inches in
diameter, at a distance of 1,000 yards requires “excellent” marksmanship
to hit. That it can be done is proved by the sinking of the German
submarine U.15 by the British Cruiser _Birmingham_ in the North Sea. The
effect of a shot carrying away the periscope is to blind the submarine,
at least in one eye, she can then be _run-down_ by the surface warship
or destroyed by rapid gun-fire at close range.
Of course, if submarines were caught napping on the surface the guns of
surface warships could quickly sink them; but another incident, similar
to that which opened the naval engagements of the Russo-Japanese War,
cannot be looked for in the naval engagements to come.
For a fleet engaged in bombarding or blockading, one of the best methods
of defence would be to lower the torpedo nets, not close round each
vessel, but suspended from “picket-boats” at a distance from the
bombarding or blockading fleet. “Picketing” is also considered a good
defence during daylight, but neither of these methods are reliable. A
submarine might be able to dive unobserved under, or past, the
destroyers acting as pickets, and it is this chance which causes these
under-water craft to be a source of constant anxiety.
The torpedo-boat destroyer should prove a nasty enemy to the submarine.
In warfare it is the duty of these 30-knot vessels to look after their
under-water opponents.
It has been suggested that internal armour could be fitted to warships
below the water-line, which would render the hulls able to withstand
mine or torpedo explosions. At present this is practically impossible,
as the great weight of this additional armour, combined with the
ever-increasing size of guns and weight of above-water protection, would
necessitate a vessel of such enormous displacement as to be quite
impossible, if the important factor—high speed—has also to be
maintained.
The defence of harbours against submarines is a problem which does not
present nearly so many difficulties as the defence of moving ships.
Portsmouth, for example, is closed by means of a submarine boom-defence,
which is stretched across the mouth of the harbour. The entrance to the
River Elbe (leading to the Kaiser Wilhelm Canal) is effectively closed
to British submarines by boom-defences, mines, and submerged wire
entanglements. Narrow waterways, such as the Straits of Dover, can be
closed by the laying of contact-mines, and even broader seas can be made
dangerous to submarines by the same method. An example of this is
afforded by the laying of a British mine-field somewhere between the
Goodwin Sands and the Dutch Coast, to prevent German submarines from
penetrating into the English Channel.
There are so many reliable means of defending harbours and narrow
waterways against submarines that it is unnecessary to say anything
further here. But to protect moving ships at sea, under all conditions,
certainly presents a most profound puzzle.