It was a well-known fact that all the Austrian ports had been mined, and that the heavy shore batteries of the enemy were more than a match for the big guns on the cruiser--that they outranged them--but, nevertheless, the crew of the Marie Theresa made what preparations were necessary with enthusiasm. It was well after nightfall when the French cruiser moved slowly between the other vessels of the allied fleet, heading for the enemy. Not a light shone aboard the vessel, and there was not a sound to break the stillness of the night. Beyond the rest of the fleet the Marie Theresa was forced to go more slowly, feeling her way cautiously to avoid being blown up by one of the many floating mines. "This is ticklish work," said Jack to Frank, they moved slowly along. "You bet," was the latter's reply. "This thing, of floating along, not knowing the next minute you are liable to be on the bottom, would try anybody's, nerves. By Jove! I can feel my hair standing end now." "I guess it's not as bad as all that," laughed Jack. "Well, I have a bad case of nerves, anyhow," replied Frank. Suddenly, at a subdued cry from forward, the Marie Theresa came to a halt. "Vessel of some sort dead ahead," the word was passed along. A moment later a voice of command rang out: "Pass the word for Mr. Chadwick and Mr. Templeton." "Wonder what's up?" asked Frank, as they made their way to the bridge, where Captain Dreyfuss was standing. "I guess we'll know soon enough," was Jack's reply. They halted before their commander and came to attention. "If I am not mistaken," said Captain Dreyfuss, pointing ahead, "that dark hull there is an Austrian vessel, whether a warship or not I cannot say. Now, the success of this venture depends upon silence. A shot from a big gun aboard that ship would mean failure for us. I have called you two lads to ask if you would like to undertake a dangerous task?" "Yes, sir," replied Jack quietly. "We shall be only too glad," said Frank eagerly. "Well, then," continued, Captain Dreyfuss, "I believe that by a quick and silent dash you may be able to board her. If You are successful in getting aboard, your first duty will be to prevent the firing of one of the big guns. Luckily, we are still far from shore, so the sounds of a hand-to-hand struggle are not likely to be overheard. Are you willing to undertake this mission?" "Yes, sir," replied both lads in a single voice. "Good! You shall have fifty men. With the effect of a surprise, I believe this should be enough." Half an hour later, while the Marie Theresa remained stationary, not even showing a light, Frank and Jack, with five small boats at their command, were creeping silently toward the Austrian vessel. Nearer and nearer they approached, and at length the first boat scraped the side of the larger vessel. So far their presence had not been discovered.