A Trireme is an ancient oar-powered vessel propelled by around 170 oarsmen. It had three layers of oars and one sail, and it was long and thin. A battering ram on the bow was used to demolish opposing ships. The ram's point was composed of bronze and could readily sever the side of a wooden ship. Behind the ram was a platform where the archers stood. The men on the lower deck were called argonauts; those on the upper deck were called navvies. The word "trireme" comes from the Greek for "three-stepped." These vessels were so named because they had three levels or decks: the gunner on the upper deck, the captain and officers on the middle deck, and the rowers on the lower deck. Each level had an entry port that allowed people to climb up and in. When full of soldiers or cargo, the trireme would have been quite crowded. However, when not in use, the trireme would be very compact - making them ideal vehicles for naval battles involving many ships. In fact, historians believe that these ships were used as prototypes for larger warships later built by other civilizations including the Romans. In addition to its size, the trireme was unique among sailing vessels because it was driven by two banks of oars that rotated in opposite directions. This required a crew of at least six men per oar, plus a helmsman at the tiller arm located near the stern.