TWO drifters, about a mile apart, with no lights to indicate their presence, were drifting idly with the ebb tide. It was an oppressively hot night in mid-August. Scarcely a ripple disturbed the surface of the sea, but the intense darkness and the absence of stars told of the heavy clouds above. The barometer had been falling rapidly for some hours and all the conditions seemed to indicate a coming storm. 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 _blase_; then the primitive net was changed for the more scientific devices already described. It required infinite patience and meant very hard work, with a _soupcon_ 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.