But he thought only of plundering and burning along the coasts, carrying off crowds of prisoners, some of whom were at once added to his crews of chained rowers. Veniero at Corfu had to steel his heart against entreaties to come to the rescue of the mainland coast population. He could not save them, and he dared not destroy his fleet in a hopeless effort. He must seize the opportunity while the Turks were occupied with their raids to sail unopposed to Messina. He decided even to risk the loss of Corfu. He was acting on the sound principle that in war all minor objects must be sacrificed to the chief end of the campaign. But he could not be sure that in obeying his original orders, and taking his fleet to Messina, he was not in another way risking his position, perhaps his life. He was leaving to the Turks the temporary command of the Adriatic. After he left Corfu they carried fire and sword along the Illyrian coast. There was a panic in Venice, and the city of the lagoons made hasty preparations for defence. But Veniero's action was soon justified. The news that the Christian armada was assembled at Messina alarmed Ulugh Ali into abandoning any further enterprises in the Adriatic, and his squadrons withdrew to join the concentration of the Turkish fleets at the entrance of the Gulf of Corinth. It was not till 23 August that the Spanish Prince arrived at Messina, took command of the assembled fleets, and proceeded at once to organize his forces, and issued his sailing and battle orders. Nearly three hundred ships crowded the harbour of Messina. There were three fleets, the Italian squadrons under the papal admiral Colonna, the Venetian fleet, and the fleet of Philip II formed of the ships of Spain and Naples. The main force of the three fleets was made up of galleys. But there were also six galleasses and some seventy frigates, the former depending chiefly, the latter entirely, on sail power for propulsion. The frigate was, in the following century and almost up to our time, what the cruiser is in the armoured navies of to-day. But in the Mediterranean fleets of the fifteenth century the _frigata_ represented only an early type, out of which the frigate of later days was developed. She was a small sailing-ship, sometimes a mere yacht, armed only with a few light guns. The frigates were used to convey stores, the swifter among them being often employed as dispatch boats. Depending entirely on the wind, it was not always easy for them to accompany a fleet of galleys. Don Juan gave up the idea of making them part of his fighting fleet. It was still the period of the oar-driven man-of-war, though the day of sails was close at hand.