Submarine Warfare of To-Day

by the auxiliary fleet during the first two years of war. It was nothing more than a long explosive tail towed submerged by a surface ship, the object being to either drag it over a submarine resting on the sea-bed, or else, if the under-water craft was moving, to so man?uvre the towing surface ship as to swing the tail close to the U-boat, when the heavy charges of T.N.T. attached to the armoured electric cable, forming the tail, would be exploded either by actual contact with the hull of the enemy, or, when sufficiently close to be effective, by the closing of a firing circuit on board the surface ship.

^{Fig. 13.—Diagram showing a vessel towing a modified sweep. This appliance consists of an armoured electric cable G towed in vertical loop under the surface. The floats D support the 100-lb. charges E, which have strikers attached. If a submarine B is lying “doggo” on the sea-bed one or other of these charges may strike her hull and the whole line then blows up, shattering everything in the surrounding sea. If the strikers fitted on the charges do not touch the submarine the whole line can be exploded at will from the surface ship by closing an electric circuit.}

Excellent in theory but very difficult of accomplishment in actual practice. The diagram given will explain the details of this elaborate contrivance, which, however, was soon discarded for more practical methods, although at least one German submarine is known to have been destroyed by it.

Lance Bombs

These little engines of destruction were intended for fighting at close quarters, and can be described here in a few lines because of their guileless simplicity. They consisted of conical explosive bombs on the ends of broom handles! A strong man could whirl one of them round his head, like a two-handed sword or battle-axe, and, when the momentum was sufficient, hurl it over the water for about seventy-five feet. On nose-diving into the sea and hitting the hull of a submarine in the act of rising or plunging, the little bomb, containing about 7 lb. of amatol, was exploded by contact.

^{Fig. 14.—A lance bomb. The wooden handle A enables the charge B (7 lb. of high explosive) to be whirled round the head and hurled a distance of about twenty yards.}

The damage inflicted on one of the earlier types of submarines by an under-water hand-grenade or lance bomb depended entirely upon what part of the vessel happened to be struck. Their sphere of usefulness was, from the first, very limited, and the advent of the big cruiser submarine, with armoured conning-tower and 5-inch guns, rendered them obsolete.

Smoke Screens

We now come to a more useful device of the purely defensive type employed to screen surface ships from submarine attack. The very simple mechanical and chemical apparatus needed for making the heavy clouds of smoke needs no description beyond that given in the text, but something must be said here regarding the methods of use.

It was not until the third year of the Great War had been ushered in by the unprecedented sinking of Allied merchantmen by German U-boats that the value of the smoke screen as a means of baffling an under-water attack was fully realised. Convoy guards were supplied with the necessary appliances for emitting the fumes with which to cover the movements of the ships under their protection, and so successful was this method of blinding attacking submarines that within a few months thousands of transports, food-ships and warships had been equipped.

When a submarine proclaimed her presence in the vicinity of a convoy either by showing too much of her periscope or by a misdirected torpedo, the guard-ships on the flank attacked immediately dropped their smoke buoys as they continued moving at full speed. By this means an impenetrable optical barrier was interposed between the attacking submarine and the fleet of merchantmen under convoy. When thus shielded from attack—a submarine values her small stock of torpedoes (six to ten) too highly to risk the loss of one or more on something she cannot even see—the mercantile fleet altered course so as to present their sterns to the attacking U-boat, while certain prearranged warships belonging to the escort proceeded to the attack with guns and depth charges.

This means of masking the movements of ships—by no means new in naval warfare—was employed with conspicuous success in the operations of Allied squadrons off Zeebrugge. Individual merchantmen, when attacked by one or more submarines, often threw out a smoke screen to avoid destruction by the big surface guns of the more modern German craft, and its use to cover the movements of transports was very frequently resorted to.

Camouflage

The use of camouflage, or the deceptive painting and rigging of ships, came first into being owing to the method employed by submarines for judging the speed of passing surface ships by the white wave thrown off from their bows. It is of the utmost importance for the commander of an under-water warship to correctly judge the speed of the vessel he is about to attack before discharging a torpedo at her. If the estimated speed is too high the torpedo will, in all probability, pass ahead of the moving target, and if it is too low it will run harmlessly astern.

To cause this to happen as frequently as possible, and valuable torpedoes to be wasted—even if the attacking submarine herself could not then be discovered and destroyed—it became advisable to paint imitation white waves on the bows of slow-moving ships in order to give the appearance of speed.

^{Fig. 15.—A camouflaged ship. It will be observed that a vessel so painted would, from a distance of several miles, give the appearance of a ship sinking while headed in the opposite direction.}

So successful was this simple form of deceptive paint-work that a special camouflage section of the naval service, with an eminent artist as its director, was formed, and all kinds of grotesque designs were painted on the broadsides and superstructures of almost every British merchantman operating in the submarine danger zone.

There was method and meaning in the seemingly haphazard streaks of black, green, blue and white. When looked at from close range only a jumble of colours could at first be seen, but if the distance was increased the effect became instantly apparent. In some cases the deceptive decoration caused big ocean liners to appear small and insignificant. In others it gave the appearance that the vessel was sinking; while quite a favourite ruse was to cause the vessel to appear as if she was travelling in the opposite direction to that which she really was. Two- funnelled ships became single-funnelled, when viewed from a distance or in a dim light, by the simple expedient of painting one funnel black and the other light grey. Liners with tiers of passenger decks had the latter obscured by contrasts of colouring which were really masterpieces of deceptive art. In fact so deceptive became almost every ship in the dim light of dawn and dusk that collisions were often narrowly averted.

It frequently occurred that paint alone was not sufficient to disguise a ship, and woodwork and canvas were resorted to. Big guns were made of drain-pipes and shields of the wood from packing-cases. Cargo boats were given the appearance of cruisers, and cruisers reduced to the appearance of cargo boats. In this way hostile submarines were induced to attack ships, thinking them unarmed and helpless, when in reality they were small floating forts. But at this point simple camouflage ceases and the famous Mystery Ship begins. Before closing this chapter, however, it must be pointed out that camouflage only came into being when the German U-boats commenced their ruthless submarine warfare.