There was, however, another difficulty to be overcome.  It was absolutely necessary that the men, who were to navigate and fight these ships, should possess some knowledge of their art; but it was in vain to expect that with the Carthaginians, so powerful and watchful at sea, the Roman ships would be permitted to cruise safely long enough to make them practised sailors and fighters.  To obviate this difficulty, they had recourse, according to Polybius, to a singular but tolerably effectual mode.  “While some men were employed in building the galleys, others, assembling those who were to serve in the fleet, instructed them in the use of the oar after the following manner:  they contrived benches on the shore in the same fashion and order as they were to be in the galleys, and placing their seamen, with their oars, in like manner on the benches, an officer, by signs with his hand, instructed them how to dip their oars all at the same time, and how to recover them out of the water.  By this means they became acquainted with the management of the oar; and as soon as the vessels were built and equipped, they spent some time in practising on the water, what they had learnt ashore.”

The necessity of possessing a fleet adequate to cope with that of the Carthaginians became more and more apparent; for though the Romans had obtained possession of all the inland cities in Sicily, the Carthaginians compensated for this by having the ascendancy by sea, and in the cities on the coast.  The Roman fleet was commanded by Cornelius Scipio, who put to sea with seventeen ships, in order to secure at Messina reception and security for the whole fleet; but his enterprise was unfortunate; for, being deceived by false information, he entered the port of Lipara, where he was blockaded by the enemy, and obliged to surrender.  This partial loss, however, was soon counterbalanced by a naval victory; for the remainder of the Roman fleet, amounting to 103 sail, being encountered by a Carthaginian fleet under Hannibal, who despising the Romans, had advanced to the contest with only fifty galleys, succeeded in capturing or destroying the whole of them.

In the mean time, the senate had appointed Duilius commander of the fleet; and his first object was to survey it accurately, and, if possible, to improve the construction or equipment of the vessels, if they appeared defective, either for the purpose of sailing or fighting.  It seemed to him, on examining them, that they could not be easily and quickly worked during an engagement, being much heavier and more unwieldy than those of the Carthaginians.  As this defect could not be removed, he tried whether it could not be compensated; and an engineer in the fleet succeeded in this important object, by inventing that machine which was afterwards called corvus.