Half-past five. To the second the British guns lifted, raining their hail of projectiles on the hostile support trenches and putting up such a tremendous barrage that no living thing could endure in that sector of bursting shells. To those of the high explosive type were added others of a terrible but totally different character. Fritz was being paid back in his own coin and with compound interest. Oft-times the cultured Huns had made use of liquid fire--a hideous barbaric means of attack. Retaliations had been reluctantly decided upon by the British authorities. At last the time-honoured maxim, "an eye for an eye, a tooth for a tooth," was being put into force. Splendid in their terrible work, the liquid fire shells burst with admirable precision over the crowded reserve trenches. Unable to retreat owing to the barrage, reluctant to face the bombs and bayonets of the British infantry as they kept pace with the lifting artillery fire, the Germans were trapped. Almost without meeting any resistance the Tommies swarmed over the hostile trenches, and soon a steady, ever-increasing stream of prisoners--men dazed with the horror of the bombardment, hungry, dirty, and devoid of spirit--set in towards the advance cages. "We're out of it this trip," thought Ralph. "There's nothing for the Tanks to do. By Jove, there is, though! A viper's nest wants flattening out." CHAPTER XIV THE COMMAND OF A TANK SECOND-LIEUTENANT SETLEY'S attention had been directed to a machine-gun emplacement that, notwithstanding the terrific pounding of the Hun lines, had somehow escaped the general demolition. It stood in a slight hollow, the dip in the ground enabling the machine-guns to fire diagonally across the line of advancing troops and, incidentally, into the crowd of demoralized Hun prisoners. Although the arc of fire was limited, the result was hardly less efficacious on that account. The harmless splaying of bullets upon the Tank's armoured side had drawn Ralph's attention to the source of the hail of small missiles. He could discern the domed tops of the three portable steel cupolas in which the machine-guns were housed. Evidently these metal defence works had been kept in a deep dug-out during the bombardment, and when the British guns lifted had been raised from the bowels of the earth--giving trouble and asking for it. Round swung the Tank, slowly, ponderously. Her "tail"--the pair of wheels used for steering purposes when on fairly level ground--was tilted clear of the crater-pitted earth. Grimly and remorselessly she set out to squash the viper's nest out of existence.