It was tricky navigation, difficult even in times of peace, to manoeuvre a craft like the _Iphigenia_ in a narrow waterway. Hampered by smoke, pounded at by guns, and blinded by search-lights and star-shells, her commander's task appeared to be super-human. Yet marvels were accomplished that night, and _Iphigenia's_ handling was one of them. Ably manoeuvred, she narrowly missed colliding with the sunken _Intrepid_, then coolly and deliberately she was grounded on the east side of the canal, thus making doubly sure that the hornets' nest was sealed. And now, their work completed, the storming- and demolition-parties from the _Vindictive_, _Iris_, and _Daffodil_ were being withdrawn. "Time for us to be making tracks, old man," shouted Alec to his chum. "Our fellows are clearing off the Mole. It's our chance to slip off with them, without being plugged by an over-excitable marine or blown sky high by a British bomb." "Yes, the show's over," rejoined the R.A.F. officer, as the pair began to retrace their footsteps. "Jolly fine stunt--eh, what?" Past the silent gun emplacements with the wiped-out crews, the two officers hastened, and descending the short flight of steps, gained the communication passage that ran practically the whole length of the Mole. For quite two hundred yards they fought their way through pungent vapours, hoping to find an exit and thus mingle with the storming-party as the men withdrew to their ships. Suddenly they found themselves confronted by a mass of blackened rubble, the stones still warm to the touch. A hasty examination showed that a heavy charge of gun-cotton had blown in the tunnel, completely cutting off the escape of Alec and his companion. "Properly dished!" exclaimed Smith disgustedly. "We're trapped!" "Tails up!" exhorted his companion. "I know of a way. Game for a swim?" "Right-o!" replied the R.A.F. officer. "Lead on, old son! It's the night of nights, isn't it?" CHAPTER XV The Passing of M.-L. 4452 "Lucky blighters!" ejaculated Lieutenant Farnborough, referring enviously to the M.-L.'s told off to rescue the crews of the block-ships. "They're on the move, by Jove!" "Wish we were on the same game," added Branscombe covetously. "I suppose we can't log an imaginary signal ordering us in support?" "Brilliant idea of yours, old man," replied Farnborough. "Half a mind to try the wheeze." M.-L. 4452, having for the time being completed her smoke-screen task, was "lying off", an interested spectator of the dash of the block-ships into Zeebrugge Harbour. Other M.-L.'s had been detailed to cover the retirement of the old _Vindictive_ and the two ex-ferry boats--if they were fortunate enough to draw away from the inferno of fire and shot, shell and poison gas; but Farnborough's command, together with six other M.-L.'s, was to stand by as a reserve rescue vessel.