Warships have also often been used as troop carriers or supply ships, such as by the French Navy in the 18th century or the Japanese Navy during the Second World War.In the time of Mesopotamia, Ancient Persia, Ancient Greece and the Roman Empire, warships were always galleys (such as biremes, triremes and quinqueremes): long, narrow vessels powered by banks of oarsmen and designed to ram and sink enemy vessels, or to engage them bow-first and follow up with boarding parties.