Among the first of the new vessels to come out was the "Philadelphia." She had no sooner arrived in the Mediterranean than she made a most unexpected discovery. She had left Gibraltar to search for some Tripolitans that were reported to be cruising somewhere off the coast of Spain. One evening after dark, off Cape de Gatt, she fell in with two vessels,--a ship and a brig. Captain Bainbridge hailed the ship, which proved to be the "Mirboka," a cruiser of Morocco; and allowing her to suppose that he was English, Bainbridge ordered her to send him her passports. The Moorish officer who came on board the "Philadelphia" fell into the snare, and told Bainbridge that the brig which he had with him was an American. This was an extraordinary piece of news, for Morocco was then at peace with the United States; yet here was one of her ships-of-war preying on American commerce. The Moors must have thought that a State which could not protect its vessels from the attacks of Tripoli need not be much respected, and that the time was ripe for them to take a hand in the plundering which their neighbors were carrying on with such success and profit; so they had sent out their cruisers, and this was the first that had made a prize. The captured ship was the brig "Celia," of Boston, whose crew and captain were at that moment confined in the "Mirboka's" hold, to be carried to Morocco and sold as slaves or held for ransom. Fortunately Captain Bainbridge had arrived just in time to rescue the prisoners; and seizing the "Mirboka," he took her with him to Gibraltar. [Illustration: COMMODORE EDWARD PREBLE.] This was the state of affairs when a few weeks later Commodore Preble, with the "Constitution," came out to take command of the squadron. He saw the situation at a glance, and he was not a man to hesitate long about taking action. If the Moors, who had seaports on the Atlantic, were not put down and the strait opened, it would be of no great use to clear the inland sea of pirates. The commodore immediately assembled all his ships, gave them orders to capture every Moorish vessel they could find, and himself proceeded in the "Constitution" directly to Tangier, in Morocco. The Emperor was expected to arrive here shortly with his army. He sent to know whether Preble would fire a salute in his honor. The commodore sent back his answer by the consul. "As you think," said he, "it will gratify his imperial Majesty, I shall salute him and dress ship; and if he is not disposed to be pacific, I will salute him again!"