[Illustration: SHE PRESENTED A PUZZLING PROPOSITION TO FRITZ]
M.B. No. 1164 B, gathering way, travelled faster than ever she had done since her acceptance trials. Her long, lean bows lifted clean out of the water, while her stern squatted deeply into the trough of her wake, and feathery shafts of spray shot out far and wide of her knife-like stem. Viewed "bows on" she presented a puzzling, nay alarming, proposition to Fritz, whose nerves were already unstrung through the effects of half a dozen narrow squeaks. All he saw was something approaching at terrific speed. He knew that there were mosquito craft that had their stings in their tails, and depth-charges were his great aversion and terror.
Nearer and nearer drew the motor-boat. Derek's resolution increased with every revolution of the propeller. He had started with the idea of "putting the wind up Fritz", but now he meant to hurl the boat bodily at the submarine, and take his chance of being picked up. A 35-foot boat travelling at seventeen knots would by its momentum shatter some of the hull plates of the submarine, but at the same time her bows would crumple up like brown paper.
Once and once only did the Lieutenant turn his head and glance at his crews. For novices they were behaving splendidly, lying stiffly, yet alertly, on the cockpit-gratings, although they could not resist the temptation of looking over the side to "see how things were going". Not a man showed a trace of fear. It was an expression of determination, of really "doing his bit" that showed itself in the knit brows of every member of the crew.
The U-boat made no attempt to do further damage to the fishing-boats. Two men at the quick-firer abaft the conning-tower swung the weapon round and let fly at the elusive target presented by the bows of R.A.F. 1164 B. Derek saw the flash, and distinctly heard the screech of the projectile ere it burst four hundred yards astern.
It was the last show. Already the U-boat's nose was dipping. The gunners, abandoning their weapon, bolted precipitately for the after-hatchway. With a resounding clang the water-tight metal cover fell in its appointed place, and the long, unsightly grey hull slithered beneath the waves in a swirl of froth and foam.
With mingled feelings of exultation and relief—exultation because he had scared the Hun into ignominious flight, and relief because he had not been compelled to sacrifice his boat and his men on the altar of duty—Derek put the helm hard-a-port, and, without slowing down, began to circle round the spot where the U-boat had disappeared. How he regretted that R.A.F. 1164 B was not fitted with depth-charges. No doubt, too, the kapitan-leutnant of the submerged craft now noticed the omission, but the chances were that he was too scared to attempt to rise to the surface and engage by gun-fire the interfering little spit-fire. He promptly crawled along a few feet above the bed of the sea—slowly, lest the following wake of the U-boat would betray its presence—until he imagined that he was safe from pursuit.
Meanwhile the fishing-boats were running for port, the dismasted craft in tow, and steered by a venerable greybeard whose silvery locks were bound with a blood-stained handkerchief, while his "mate", otherwise his fourteen-year-old grandson, was nursing a badly-lacerated leg, and thanking his lucky stars that he was not one of Germany's sons.
Having satisfied himself that the fishing-boats were out of danger Derek steered for the harbour. Just as he crossed the bar he saw two coastal airships making seawards.
"That's good!" he remarked to the coxswain. "Those fellows will do some very efficient strafing, unless I'm much mistaken. It hasn't been a bad run, has it?"