"Hist!" whispered Seton, holding up a warning hand. Although it was night, the stars enabled the men, accustomed to the sombre conditions, to see with comparative ease. "What is it?" whispered Smith. In reply Seton inserted the point of the spike into a crevice and pressed his ear lightly against the blunt end. His suspicions were not ill-founded. The metal, acting as a transmitter of sound, enabled him to detect footsteps in the corridor beneath. "Rough luck," remarked the pilot in a low tone. "We'll stand fast for a bit," decided Seton. "It may be that it's only a patrol or a party drawing stores. It's not far from midnight now." As he spoke a gun barked a few yards off, quickly followed by another and another, until the masonry quivered and swayed with the terrific detonations. Both men made their way to the window, which, unaccountably, their gaolers had not closed by means of the metal shutter. Seaward avast bank of fog--whether natural or artificial the watchers had no means of telling--was punctured by rapid and vivid flashes of light. Star-shells and search-lights illumined the sky. Shells were screeching and bursting everywhere, until the sea and sky seemed blotted out with smoke and far-flung columns of spray. Suddenly Seton gripped his companion's arm, causing him to wince with pain, and pointed to an indistinct grey mass looming through the fog. It was a vessel, blazing away with quick-firers and heading straight for the Mole. "Thank God for that sight!" ejaculated Alec fervently. "This is the beginning of St. George's Day with a vengeance." CHAPTER XIII The Attack on the Mole "It all depends upon the weather," remarked Lieutenant-Commander Farnborough. "This is absolutely the best we've had, and our third attempt--three for luck." It was a quarter to five on the afternoon of Monday, the 22nd of April. The main force of the vessels operating against Zeebrugge and Ostend were on the point of starting from the concentration base, upon their hazardous enterprise. The composition of the operating craft was of a truly diverse nature. Off the Goodwins came the old _Vindictive_, disguised almost out of knowledge. Her mainmast was down, the massive spar being fashioned into a huge "bumpkin" to fend her stem off the masonry of the Mole. On her foremast and above her conning-tower were box-like structures containing flame-projecting apparatus, Lewis-guns, and other devices conjured up by the Great War. Along her sides were large "brows" or gangways, together with a formidable array of hawsers and chains terminating in specially constructed grapnels. Astern and in tow of her were _Iris_ and _Daffodil_, two ferry-steamers well known to the inhabitants of Liverpool and Birkenhead, and now carrying passengers of a very different sort from those to which they were accustomed. Following were the block-ships _Thetis_, _Intrepid_, _Iphigenia_, _Sirius_, and _Brilliant_, the paddle mine-sweeper _Lingfield_, and five M.-L.'s.