She was now only seven sea miles distant from the Dean Tail Buoy. Within ten minutes of the receipt of the wireless she was on the spot—one of the very first of a regular hornet flotilla bent upon adding yet another of Von Tirpitz's pets to the "bag".
For the next quarter of an hour it looked as if a novel kind of marine waltz was in progress. Nearly a score of swift vessels were executing fantastic movements at full speed, circling and interchanging positions until it seemed as if collisions were impossible to avoid.
Their object was to thoroughly bewilder the already doomed U-boat, for, if possible, her capture in a practically intact condition was desired. In very deep water, salvage of a sunken submarine was out of the question; here, in a comparatively shallow depth, and close to an important naval base, to which the prize could be taken with little trouble, the opportunity for capture rather than instant destruction was too good to be missed.
Suddenly a cloud of white smoke shot up from the sea. Its appearance was greeted by hearty cheers from the patrol vessels. It was a signal that the U-boat, in her attempt to find deep water, had floundered blindly into the trap. Over and over again the hunters passed, towing non-explosive grapnels, until it was certain that the prey was helpless in their toils.
Then, in obedience to an order from the senior officer, the swift vessels withdrew for nearly three cables' length from the spot where the boat lay. Two slow but powerfully engined trawlers approached at a cable's length abreast, towing the bight of a massive steel hawser between. Doing little more than drift with the tide they crept past the submerged U-boat, one on either side of the mark-buoy that indicated her position.
Presently the strain on the hawser increased. It was only by making full use of the twin-screws that the trawlers were able to prevent themselves from swinging together. The steel rope stretched until it resembled two metal bars which bore silent testimony to the strain.
Just then the two vessels shot ahead. Although the hawser was still intact, it no longer took any strain. But its work was done. The bight, engaging the conning-tower of the unterseeboot, had turned the submarine on its side. In the space of a few seconds the deadly fumes from the capsized batteries had almost painlessly accounted for the crew of the U-boat, who themselves had neither pity nor consideration for the hapless victims, men, women, and children, massacred against all dictates of humanity and convention of civilized warfare.
"A bit of work for the dockyard lighters to-morrow," commented Sub-lieutenant Barry, as the Capella parted company to resume her run up-Channel. "They'll raise the U-boat, and take her into dry dock, before the sulphuric acid has had time to do much damage to her mechanism."
"I shouldn't be surprised if there were another U-boat knocking around," remarked Vernon. "From our limited experience we know that they work either in pairs or threes."
"Then the worse for them," rejoined Barry. "It would be a great wheeze to bag two of them in one day. Desperate diseases need desperate remedies, you know."