The hemiolia or hemiolos was a light and fast warship that appeared in the early 4th century BC. It was particularly favoured by pirates in the eastern Mediterranean, but also used by Alexander the Great as far as the rivers Indus and Hydaspes, and by the Romans as a troop transport. It is indeed very likely that the type was invented by pirates, probably in Caria. Its name derives from the fact that it was manned by one and a half files of oarsmen on each side, with the additional half file placed amidships, where the hull was wide enough to accommodate them. Thus these ships gained motive power without significantly increasing the ship's weight. Given their lighter hulls, greater length and generally slimmer profile, the hemiolia would have had an advantage in speed even over other light warships like the liburnian.