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.

“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 manoeuvring 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.

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.