Later, in the days of the Roman supremacy, the trading-ships were as important to the country as its soldiers, for nearly every free man was in the army, and the slaves made poor farmers. A large part of the grain, as well as cattle, to supply the wants of the people, had to be brought from Egypt, which was pretty sure to have “corn,” as the Bible calls it, when the rest of the world was suffering from short crops. Egypt supplied grain to Rome during the second Punic war, thus enabling her to resist the invasion of Carthage, and it is possible that Rome’s later political alliance with Egypt was largely due to her interest in Egyptian crops. Large fleets of grain-ships, convoyed by armed vessels, were continually passing between the African coast and the Tiber, and so many were the risks they ran of wreck or capture, that the arrival of a flotilla with its precious freight of food was always a cause of rejoicing, at any rate, among the poor. These merchant ships of classical times were broader and heavier than the war-galleys, and although they carried a few oars to help themselves in a difficulty, they ordinarily moved by means of sails, probably lugs. One of the grain-ships plying between Egypt and Italy about 150 A. D., according to Lucian, was one hundred and eighty feet long, slightly more than one fourth as broad, and forty-three and a half feet deep inside,— more like a barge than a “ship.” The largest used in this trade would carry about two hundred and fifty tons. The transports that accompanied one of Justinian’s fleets, A. D. 533, are stated to have carried one hundred and sixty to two hundred tons of supplies each. These Roman vessels were made of pine, and were coated with a composition of tar and wax, then painted, often with elaborate decorations in bright colors, with pigments mixed with melted wax. Now and then one was built of truly vast proportions, as that one which brought from Egypt to Rome the first of the stolen obelisks. [Illustration: A CAPTAIN IN THE MERCHANT MARINE.]