It was obvious that the one chance of escaping their terrible unseen foe was to obey the signal. By this time crowds of small craft of every description had come off from both shores to the rescue of those who had gone down with the ships, so the Admiral did what was the most practical thing to do under the circumstances--he dropped his own boats, each with a crew, and ordered the _Victorious_ and _Mars_ to do the same, and then gave the signal for full speed ahead. The great engines panted and throbbed, and the squadron moved forward with ever-increasing speed, the cruisers and destroyers, according to signal, running ahead of the battleships; but before full speed was reached, the _Mars_ was struck under the stern, stopped, shuddered, and went down with a mighty lurch. This last misfortune convinced the Admiral that the destruction of his battleships could not be the work of any ordinary submarine, for at the time the _Mars_ was struck she was steaming fifteen knots and the underwater speed of the best submarine was only twelve, saving only the _Ithuriel_, and she did not use torpedoes. The two remaining battleships had now reached seventeen knots, which was their best speed. The cruisers and their consorts were already disappearing round Foreland. There was some hope that they might escape the assaults of the mysterious and invisible enemy now that the airship had been destroyed, but unless the submarine had exhausted her torpedoes, or some accident had happened to her, there was very little for the _Prince George_ and the _Victorious_, and so it turned out. Castellan's strict orders had been to confine his attentions to the battleships, and he obeyed his pitiless instructions to the letter. First the _Victorious_ and then the flagship, smitten by an unseen and irresistible bolt in their weakest parts, succumbed to the great gaping wounds torn in the thin under-plating, reeled once or twice to and fro like leviathans struggling for life, and went down. And so for the time being, at least, ended the awful work of the _Flying Fish_. Leaving the cruisers and smaller craft to continue their dash for the open Channel, we must now look westward. When Vice-Admiral Codrington, who was flying his flag on the _Irresistible_, saw the flashes along the Hillsea ridge and Portsdown height and heard the roar of the explosions, he at once up-anchor and got his squadron under way. Then came the appallingly swift destruction of Hurst Castle and Fort Victoria. Like all good sailors, he was a man of instant decision. His orders were to guard the entrance to the Solent, and the destruction of the forts made it impossible for him to do this inside. How that destruction had been wrought, he had of course no idea, beyond a guess that the destroying agent must have come from the air, since it could not have come from sea or land without provoking a very vigorous reply from the forts. Instead of that they had simply blown up without firing a shot.