So it came to pass that the D-16 laid herself out on a course for the Kiel canal, the waterway which the Germans had constructed at such great expense, that her fleet in the North Sea and her fleet in the Baltic might ever be in touch with one another. An attempted passage of the Kiel canal by a hostile ship or ships had been considered out of the question by all naval authorities. Such an attempt, it was claimed, would be too foolhardy and would be bound to end in destruction. Nevertheless, Lord Hastings, while realizing all this, was not the man to turn from a purpose once he had made up his mind. He realized the full danger of the situation much more than did Frank or Jack, who, carried away by the opportunity of participating in what would be one of the greatest naval ventures of history, had at once lost sight of all possible danger. Deep, deep down in the sea the D-16 made her way from the harbor of Heligoland, diving far beneath the mines that protected the German fortifications. And in her wake she left three sunken German ships of war and another so badly damaged that she would be out of commission for many months. "I am willing to bet," said Frank, "that the Germans either lay the raid to internal troubles or else claim that a British submarine flotilla of at least 20 vessels participated." "Right you are," agreed Jack, "and they will probably add that the enemy was driven off with great loss, more than half their number being placed hors du combat." "At the same time," interrupted Lord Hastings, "saying that 'our losses were insignificant.'" "Well," said Frank, "I don't suppose the government can afford to let the people know just how serious their predicament is." "That's about the size of it," agreed Lord Hastings. The speed of the D-16, once she was beyond the German mine field, was increased to 20 knots, and she headed directly for the entrance to the Kiel canal. Frank and Jack both turned in. With the coming of morning the D-16 was but a few miles from her goal, and Lord Hastings accordingly ordered the speed slackened that a close watch might be kept for mines. At eight o'clock Lord Hastings checked the speed of the vessel and ordered that it be brought to the surface. "But surely we are not through the canal yet?" protested Jack. "No," was the reply, "but we are almost at the entrance, and I want to take a look about." Jack did not protest further, and when the submarine again floated on the surface of the sea he followed his commander to the bridge. There a startling sight met their gaze, for not a hundred yards away, riding gently with the even swell of the sea, lay a second submarine and she flew the Red, White and Black of Germany. "Below quick!" cried Jack. But Lord Hastings laid a hand on the lad's arm as he darted for the hatchway. "Wait a minute," he said. "There doesn't seem to be any one on guard, or we should have perceived some sign of life."