Confident of security behind the mass of mines and submarine traps spread ingeniously across the harbor entrance, devoting their attention almost solely to the artillery duel with the dreadnoughts outside, the German cruiser knew naught of the stealthy torpedo from the daring _Monitor_ until it shot suddenly forward below the surface of the water, revealed in the glare of her own searchlight. But it was too late then to avoid the deadly missile and it struck home abaft the engines and directly at the after magazine chambers. With a great roar and the upheaval of a mighty column of water the torpedo exploded against the side of the warship. One carefully aimed shot from the leading American submarine had laid low a ten-thousand-ton cruiser! "Quick, down we go!" shouted McClure to his navigating officer. The _Monitor_ shot down now out of sight, and the helm was thrown hard to starboard. That one shot was sufficient to apprise the Germans of the presence of submarines and McClure realized full well he would be a marked man next time he showed his periscopes above water. It was in mid-channel that the _Monitor_ ventured to the surface again. The periscopes showed another vessel, a second line battleship of the pre-dreadnought type, off the starboard beam. Undaunted by the hail of lead slugs that splashed the sea all around, the _Monitor_ swerved and ran straight for the battleship's bows. "This one ought to settle scores for that poor old mine sweeper!" yelled the Yankee skipper as he sighted through the periscope glass on the wide target in front of him not more than six hundred yards away. "Give it to 'em, Mack! Give it to 'em!" cried Jack. Again, a torpedo leaped from the bowcap of the _Monitor_ and hurled its ton and a quarter of steel gray mass directly upon the port bow of the German craft. As the _Monitor_ dived away again her captain beheld the battleship listing badly, going down by the bow at a rapid rate. "Two strikes!" he exclaimed enthusiastically. "Some night!" gasped Ted as he clutched the foot rail that ran up the side of the conning tower. "And some battle!" responded Jack at his side. With engines slowed down the _Monitor_ ran along a hundred and fifty yards and then turned her nose upward again for another stab at the German fleet. As her periscopes cleft the crest of the waves again and she emerged into the arena of activity McClure caught sight of a destroyer off the starboard bow not more than five hundred feet away. A searchlight on the forward deck of the German vessel swept the water in front of the _Monitor_ with a long white finger of light that fell in a moment upon the eyes of the American submarine. "A destroyer driving directly at us at full tilt with all her guns in action!" roared McClure.