"The fortunes of war," said Jack, more quietly now. "It is a terrible thing." Further conversation was interrupted by the sound of another terrific explosion. Startled, the boys turned in the water just in time to see the last German destroyer disappear beneath the sea. "Good!" exclaimed Jack, in fierce joy. "I am glad of that." Frank also gritted his teeth, and muttered fervent congratulations to the British gunners. And now the British ships proceeded on their course. None had been seriously damaged. They turned their backs upon the scene of the engagement and made off in the direction from which they had come. The boys shouted loud and long for assistance; but their cries were not heard aboard the British ships of war, which, gradually gathering more headway, steamed off to the south. Not until they were almost out of sight did the lads cease their shouting, and resign themselves to their fate. In despair, they turned to each other for comfort. Jack was first to speak. "Well, Frank," he said quietly. "We shall soon join Lord Hastings and our other good friends in a place where there is no war and no losing of friends." "Isn't there something we can do?" asked Frank, trembling with cold. "I am afraid not." There was a sudden stirring of the water beneath them. Jack cried out suddenly: "What's that?" Frank had regained his coolness now. "Probably a shark come to finish us up quickly," he replied calmly. Both lads, with a last effort, swam desperately from the place. But suddenly the waters of the North Sea parted, and a long, cigar-shaped object came to the top and rested lightly on the water. "What is it?" asked Jack again in no little alarm Before Frank could reply, a man suddenly appeared on the top of the object, apparently from nowhere, and glanced about. He espied them, and as suddenly disappeared. He reappeared almost in an instant, however, followed by another. And now both lads discovered what the object was, an object that had arrived just in time to save them from a watery grave. They could see that the two men wore the uniform of the German navy. The long, cigar-shaped object was a German submarine. CHAPTER IV ABOARD THE X-9 There was a hoarse command from aboard the submarine, and a moment later a small boat floated alongside the two German officers who clambered in. Frank and Jack swam toward them as rapidly as their exhausted condition would permit. "What are you two lads doing here in the middle of the North Sea?" asked one of the officers in great surprise, after the boys had been pulled aboard the small boat. "We're here because our ship was sunk by one of your blamed torpedo boats," replied Jack, with some heat. "Only one sunk?" inquired the officer in excellent English. "Just one; it seems to me that is enough." "Well, I agree that it is better than none," said the German officer. "We'll sink them one at a time. How many of our ships engaged you?"