CHAPTER XIII. A SUBMARINE RAID. Creeping stealthily forward beneath the water, the D-16 was advancing to the attack. Lord Hastings stood at the periscope and Jack was at his elbow. The vessel was prepared for action, and the crew stood at attention. Lord Hastings touched Jack on the shoulder. "Tell the watch to keep a sharp lookout for submarines," he said. "The chances are that they have been thrown out in front of the battleships." Jack departed and gave the necessary order, after which he returned to his position. It was just after dusk on the evening following the day on which Frank had been captured. All day and all during the previous night the D-16 had kept near the bottom, maneuvering first this way and then that, and not once had they caught sight of an enemy's submarine, nor had they risen to the surface for a look about. But now Lord Hastings had decided upon action. He had idled long enough. Therefore, after preparing for action, the D-16 had risen sufficiently to give her periscope free play, and the commander now gazed over the water. "German battleship ahead," he called to Jack. "Slow to five knots." The speed of the submarine slackened. "Take the lookout yourself, Mr. Templeton," was the next command. Jack did as commanded, and peered intently ahead. In the dark murky water he could see but a few feet, for it had not been deemed advisable to turn on the searchlight and thus make a target for the enemy's submarines. However, the D-16 was progressing at a snail's pace and could be halted upon the instant. Therefore, there was not much danger of encountering any obstacle, providing the man on lookout attended to his duties properly. Suddenly a dark object loomed up ahead. Quick as a flash Jack signalled the engine room and the D-16 came to an abrupt stop. Jack reported to Lord Hastings. "Dark object right ahead that looks like a submarine submerged," he said calmly. "Give the order to back away a hundred yards, then fire a torpedo into her," was Lord Hastings' command. Slowly the D-16 backed away from the dark object ahead, and an instant later a sharp "click" gave evidence that a torpedo had been launched. Immediately Jack flashed on the searchlight. While his eyes could not follow the flight of the torpedo, the huge and powerful searchlight showed him the result. Struck squarely amidships the German submarine, for such the object ahead proved to be, seemed to split wide open. The water poured in in a dense volume, and suddenly the enemy sank. Jack shuddered. "Must be a terrible death," he muttered to himself. "However, if we had not sunk her she would probably have sunk us." Once more he reported to Lord Hastings. "Way clear now, sir," he said. "Good," was the reply. "Make your speed five knots and continue your course."