The duty of these two vessels was to watch lines of cunningly laid submerged nets (described in an earlier chapter) and to guide the few merchant ships which passed that way through the labyrinth of these defences, laid temporarily as a trap for the wily "Fritz" if he should chance to be cruising in the vicinity.

The drifters were adequately armed with guns and depth charges to attack any such monster of the deep which betrayed its presence by becoming entangled in the fine wire mesh and so attaching to itself a flaming tail, which would then be dragged along the surface, marking it as a target for all the pleasant surprises lying ready on the decks of the patrols.

Fishing for Fritz was a popular sport in the anti-submarine service until the "fish" became shy and its devotees blasÉ; then the primitive net was changed for the more scientific devices already described. It required infinite patience and meant very hard work, with a soupÇon of danger thrown in. For when the tons of steel wire-netting, with its heavy sinkers and floats, had been laid, days were spent in watching and repairing, then endless resource employed to induce a submarine to enter the trap. Occasionally the voyage ended in an exciting chase, with the flaming buoy as the guiding light.

It was in the early period of the war, when Paris was still threatened by the Teutonic armies and the Allies waited confidently for the clash of the great battle fleets. Every dark night on the northern sea eyes and ears were silently watching and listening for the comings and goings which would herald the storm. The strain was great though the work was not spectacular, for all knew that the safety of England, or at least its freedom from invasion, might, for one brief historical instant, depend on the vigilance and nerve of that heterogeneous, irregular horse, the sea patrols.

The great cruiser squadrons were scouring the North Sea. Battle seemed imminent, and that vague wave of human electricity which passes along the firing line before the attack at dawn, and even extends to the lines of communication, was in the air on this dark night in 1915.

Six bells had just struck when a faint, cool breeze swept across the surface, and a few minutes later the first vivid flash of lightning forked the eastern sky. There was a scramble for oilskins on Drifter 42 as the rain came hissing down like a flood released. The storm was severe while it lasted. The thunder rolled over the placid surface. Lightning darted athwart the sky, illuminating the black void beneath. For about thirty minutes the sky blazed and roared, then the hiss of the rain ceased and the storm moved slowly northwards, but one of the final flashes revealed something low down on the surface moving stealthily forward. So brief was the glimpse obtained, however, that it seemed merely a phantom—by no means uncommon occurrences when men have been watching for years. When the next flash came the surface of the sea around was clear.

As was usual in such cases, half the watch on deck could swear they had seen it, while those who were not looking ridiculed the idea, so the C.O. said nothing and took precautions. The watch below was called and the powerful little gun on the fore-deck manned. Then all waited in silence, listening intently for the curious, creaking noise of a submarine under way.

In those early days of hostilities there were no elaborate hydrophones for detecting the approach of submarines under the water, and the only hope of a warning came from the possibility of the under-water vessel breaking surface momentarily. The uselessness of the periscope for navigation during darkness, which at present forms the principal limitation of submarines, made it distinctly likely that she would cruise on the surface at night, and if forced to dive would be more or less compelled to quickly rise again in order to ascertain the position of her enemy before it would be possible to fire a torpedo with any chance of success.

For these reasons all eyes and ears on the drifter were strained to catch the first glimpse or sound, and dead silence was maintained. It is in times like this that one discovers how acute the senses become when danger lurks in the darkness around. Things undetectable under normal conditions can be seen or heard distinctly when life depends on the intelligence so gained.

Long minutes of silence slipped by and nothing occurred; then came the distant and familiar creaking noise, almost inaudible at first. The gun's crew braced themselves for the stern work ahead. On the rapidity and accuracy of their fire not only their own lives, but also those of their comrades, would probably depend. The gun-layer bent his back and glanced along the grey tube to the tiny blue glow of the electric night sight. The shell was placed in the open breech. Then came those interminable seconds before an action begins.

The tension would have been almost unsupportable had nearly all of the crew not grown accustomed to life hanging in the balance on the wastes of sea.

A flicker of light, at first almost spectral, appeared from out of the darkness some 500 yards to starboard. It grew almost instantly into a bright white flare, illuminating the surface of the black water as it moved along. The pungent smell of burning calcium floated over the sea and the drifter's engines began to throb heavily.

The tension relaxed, a subdued cheer broke from the crew of the drifter as she gathered speed, and the Morse lamp winked its order for concerted action to the other drifter somewhere in the darkness around. An answering dot-dash-dot of light appeared from away to starboard and the chase commenced in earnest.

A few minutes later the glare from the calcium buoy, now being towed through the water at several knots, shone on the faces of the crew as they trained their gun ahead, but the submarine was under the surface and, although probably quite unaware of the flaming tail which was betraying her movements, appeared to know that she was being hunted by surface craft. After running straight ahead for a few minutes she turned eight points to the eastward in an attempt to baffle pursuit.

The chase was a fairly long one, as the speed of the drifters was not sufficient to enable them to gain rapidly on their quarry, but the flexibility of the steam-engine gradually gave the surface ships the advantage and they crept up level with the light. Then, with their boilers almost bursting and flames spouting from the funnels, they drew ahead until over the submarine itself. Depth charges were dropped from the stern of the drifters. The water boiled with the force of the explosions and the light on the buoy went out. Still the drifters held their course in the now pall-like blackness, and other bombs splashed into the water astern, to explode with a dull vibration a few seconds after they had sunk from the surface.

The engines of the two small surface ships were shut off and every ear became alert, but no sound broke the stillness of the summer night, except the rumble of distant thunder and the gentle lap of the sea against the sides. Morse signals winked from one ship to the other and back again. When due precautions had been taken against a further surprise attack, the chivalry of the sea called for a search to be made for possible survivors. This was done with the aid of flares, but only oil and some small debris were found. Dan-buoys were dropped to mark the spot and soundings taken. Twenty-four fathoms deep was added to the report of the action, and a few days later a diver reported having found the wreck of the U-C 00.