The Romans, although they were so powerful in land warfare, were not strong in naval achievement until after the First Punic War. In this war they learned the art of naval construction from their enemies, the Carthaginians. A Carthaginian "quinquereme," or boat with five banks of oars, drifted to the Roman coast. The Romans copied it, set up frames on dry land in which crews were taught to row, and in sixty days from the time the trees were felled they had built and manned a fleet. Later the Romans used grappling hooks with which they bound together their own and an opposing ship. They then boarded the enemy's vessel and carried on the fight at close quarters. These tactics gave the Romans command of the sea, and their war galley came to be the supreme object of terror in the naval history of Roman days.
Sails and wind superseded rowers as the motive force of ships. Then came steam. But after gunpowder and steam had worked a revolution in the modes of naval combat, vessels of war continued to be made of wood.
The first fight between iron ships in the history of the world was fought on the ninth of March, 1862, in Hampton Roads, near Norfolk, Virginia, during the Civil War in America. The battle was the combat between the _Merrimac_ and the _Monitor_. This engagement marked the end of wooden navies. Thenceforth the nations of earth were to make their warships of iron and steel.
Among the largest battleships built for the United States navy are the _Delaware_ and the _North Dakota_. Each of these battleships is five hundred and ten feet long, a little more than eighty-five feet wide, sinks to the depth of nearly twenty-seven feet in the water, and travels at the rate of twenty-one knots per hour. Each vessel weighs twenty thousand tons, and is armed with ten great guns a foot in diameter at the mouth. The _North Dakota_ required 4688 tons of steel armor at a cost of more than four hundred dollars per ton. Each of its great twelve-inch guns cost nearly $110,000, weighs fifty-two tons, and hurls a projectile weighing 850 pounds a distance of twelve miles. Three hundred and eighty-five pounds of powder are consumed at a single discharge. At a distance of more than a mile and a half the projectiles of the _North Dakota_ will penetrate steel armor to a depth of nearly twenty inches. When these projectiles leave the guns, they fly through the air at the rate of 2,800 feet in a second. When one hundred shots have been fired from one of these guns, it is worn so that it will be useless until repaired. The cost of a single discharge from one of these guns is about $350.