A uniformed figure appeared above the poop-rail of the captured tramp. The officers of the British vessel, keeping him under observation by means of the powerful glasses, could see him gesticulating to the submarine. The latter began to lose way before going astern.
Now or never. A gap of barely fifty yards lay betwixt captor and prize. At the word of command the gun-layers of the two for'ard quick-firers bent over their sights. The two reports sounded as one as the projectiles screeched on their errand of destruction.
One shell hurtled within a few feet of the top of the conning-tower, sweeping away both periscopes in its career. The other struck the raised platform in the wake of the conning-tower, exploded, tearing a jagged hole in the hull plating. Before the smoke had time to clear away the U-boat had vanished for all time, only a smother of foam and a series of ever-widening concentric circles of iridescent oil marking her ocean bed.
Viewed from the deck of the Portchester Castle there could be no doubt as to the fate of the modern pirate. Simultaneously a deafening cheer burst from the throats of the British crew. It was a feat to be proud of, sending a hostile submarine to her last account before the Portchester Castle was three days out of port.
When within signalling distance of the Douro the latter rehoisted her colours and made the "NC" signal, "Immediate assistance required".
"Perhaps the Huns have already begun to scuttle her," remarked Tom Webb. "Although I can't detect any sign of a list."
"We'll soon find out," replied Osborne. "Pipe away the cutter," he ordered, in response to a sign from the skipper.
Quickly the falls were manned, the boat's crew, fully armed, scrambling into the boat as it still swung from the davits. Sub-lieutenant Webb, being the officer in charge, dropped into the stern-sheets.
"Lower away."
With a resounding smack the cutter renewed a touching acquaintance with the water. The falls were disengaged, and, to Webb's encouraging order, "Give way, lads!" the boat drew clear of the now almost stationary ship, which was within a couple of cables' lengths of the Douro.