had several types of merchant galleys that specialized in various tasks, out of which the actuaria with up to 50 rowers was the most versatile, including the phaselus (lit. "bean pod") for passenger transport and the lembus, a small-scale express carrier. Many of these designs continued to be used until the Middle Ages. Roman Imperial era The Battle of Actium in 31 BC between the forces of Augustus and Mark Antony marked the peak of the Roman fleet arm. After Augustus' victory at Actium, most of the Roman fleet was dismantled and burned. The Roman civil wars were fought mostly by land forces, and from the 160s until the 4th century AD, no major fleet actions were recorded. During this time, most of the galley crews were disbanded or employed for entertainment purposes in mock battles or in handling the sail-like sun-screens in the larger Roman arenas. What fleets remained were treated as auxiliaries of the land forces, and galley crewmen themselves called themselves milites, "soldiers", rather than nautae, "sailors". The Roman galley fleets were turned into provincial patrol forces that were smaller and relied largely on liburnians, compact biremes with 25 pairs of oars. These were named after an Illyrian tribe known by Romans for their sea roving practices, and these smaller craft were based on, or inspired by, their vessels of choice. The liburnians and other small galleys patrolled the rivers of continental Europe and reached as far as the Baltic, where they were used to fight local uprisings and assist in checking foreign invasions. The Romans maintained numerous bases around the empire: along the rivers of Central Europe, chains of forts along the northern European coasts and the British Isles, Mesopotamia, and North Africa, including Trabzon, Vienna, Belgrade, Dover, Seleucia, and Alexandria. Few actual galley battles in the provinces are found in records. One action in 70 AD at the unspecified location of the "Island of the Batavians" during the Batavian Rebellion was recorded, and included a trireme as the Roman flagship. The last provincial fleet, the classis Britannica, was reduced by the late 200s, though there was a minor upswing under the rule of Constantine (272–337). His rule also saw the last major naval battle of the unified Roman Empire (before the permanent split into Western and Eastern [later "Byzantine"] Empires), the Battle of Hellespont of 324. Some time after Hellespont, the classical trireme fell out