The Roman Navy

How quickly and in how many boat lengths could a trireme make a 180 degree turn?

Model of a Roman bireme

While it is the Roman legion that leaps to mind when discussing Rome’s military might, the navy also played a vital role during the later Republic and early Empire.

The Roman Navy before the Empire
The early Romans were not a seafaring nation, and the early Republic did not have an effective navy. That changed with the First Punic War (264-261 BC) against the maritime city of Carthage. By 256, Rome had built a navy of 330 ships. After 202 BC, the end of Second Punic War (when Hannibal crossed the Alps with elephants), the standing Roman navy was not maintained. Rome relied on ships provided by treaty with the maritime cities of Pergamum and Rhodes (in/near present-day Turkey).

Major problems with pirates led once more to the establishment of a standing navy. In 67 BC, the renowned general and former consul, Pompey, was charged by the Senate with ending the pirate raids that endangered the grain supply of Rome. By commandeering Greek galleys and organizing them into 13 fleets for an organized sweep, he scattered the pirates in 40 days. After only three months of naval action, the final battle at the main stronghold of the Cilician pirates essentially ended large-scale organized piracy in the Eastern Mediterranean. Pompey took 20,000 captives, captured 90 ships, and recovered enormous treasure.

The navy played a vital role as the Republic came to an end. As many as a thousand ships of the Roman navy were involved in the Civil War between Pompey and Julius Caesar that ended in with Pompey’s death in 48 BC.

The Battle of Actium by Laureys a Castro (1672)

The Battle of Actium by Laureys a Castro (1672)

After Julius Caesar’s assassination on the Ides of March in 44 BC, war broke out between Marcus Antonius and Octavian (Caesar’s heir by adoption). Sea power was crucial in the battle of Actium, which was decisive in determining the winner. With the main forces of Anthony and Cleopatra on the northwest coast of Greece, Octavian’s admiral, Vipsianus Agrippa, cut off their supplies. More than a hundred of Anthony’s fleet of 200 ships surrendered to Octavian after Anthony and Cleopatra escaped by sea.

The Roman Navy during the Empire
Octavian became Caesar Augustus, the Republic became the Empire, and the navy remained an important part of the Roman military system during Augustus’s rule.

The two major fleets were based in Italy. The Misene was based in the Bay of Naples with 10,000 men patrolling the western regions of the Italian coast and the Mediterranean. The Ravennate had 5000 men patrolling the Adriatic Sea and the eastern Mediterranean. There were 8 provincial fleets, some of which were based on rivers: Alexandrina (Egyptian coast and the Nile), Syriaca (Syrian coast and Aegean Sea), Moesica (eastern Danube and northern Black Sea), Pannonica (middle and upper Danube), Lauriacensis (upper Danube near Enns River), Pontica (southern and eastern Black Sea), Germania (Rhine River into the North Sea), and Britannica (English coastline).

Roman fleet map

Misenum, on the northern shore of the Bay of Naples, was the headquarters of the main fleet (classis) for almost 400 years. It was established for Augustus by Agrippa after the war with Anthony and Cleopatra. There were 10,000 men and more than fifty ships based in this strictly military harbor in AD 69. Detachments were based at several major ports along the western coast, including Ostia, the main port at the mouth of the Tiber that served Rome itself.

The second Italian fleet was established in 25 BC at Ravenna on the Adriatic Sea at the Po River. Like Misenum, it was strictly a military harbor. It had mostly triremes and a contingent of about 5000 men in AD 69.

After the end of the 2nd century, the old policy of assembling a navy for each emergency was resumed. There were ten fleets in AD 230. By 284, only the two Italian fleets remained. Piracy had again become a major problem. Under Diocletian, the old fleets were replaced with much smaller flotillas, each based in a single port and responsible for patrolling a small area near the home port. When Constantine and Licinius fought over a splitting empire in AD 324, the imperial navy of Augustus was no longer recognizable.

The Warships
Roman warships (naves longae) derived from Greek galley designs. In the ocean-going fleets, the three main designs were trireme, quadrireme, and quinquereme. During the Republic, the quinquereme was the standard ship. After the battle of Actium at the start of the Empire, the trireme became the main ship.

The ships were long and narrow, usually with a 7:1 proportion. None are known to have been longer than 200 feet. They rode low in the water and were not very stable in high seas.

While merchant ships were sheathed with metal (often lead), there is no evidence the warships were. In the winter, they were hauled ashore and often stored under cover to protect them.

Power was provided by oarsmen and sails. A trireme had three banks of oars with 150 rowers. Each rower pulled his own oar. The quinqueremes are believed to have had five men pulling each massive oar, giving a rowing crew of 400. For the triremes, speeds up to nine or ten knots were possible in short spurts (ramming speed). One large sail midship, with a mast that could be lowered at sea for battle, and another smaller sail near the bow could provide propulsion when precise control was not needed.

A Greek trireme, the Olympias, was constructed according to a 5th or 4th century BC design in 1985. With a length of 121 feet (40 m) , a width of 17 feet (5.5 m), and a beam (height) of 18 feet (5.3 m), it weighed 70 tons. Its maneuverability was astounding. A crew of 170 oarsmen demonstrated a 180 degree turn within one minute with a curve no wider than 2 ½ ship-lengths by the oarsmen on one side not rowing while those on the opposite side rowed. In sea trials, steady speeds of 2.15 knots (2.5 mph or 4.0 km/hr) and short-burst speeds of 9 knots (10.6 mph or 17 km/hr) were achieved. Not quite enough for the captain to waterski, no matter what the old joke says.

provincial fleet ships on Trajan's column

Relief from Trajan’s column: Smaller ships of the provincial fleet used in the Dacian war

Smaller ships were often used in the provincial fleets. One popular ship was the liburna, a small, fast ship modeled on those used by the Liburni pirate tribe. One or two banks of oars were manned by two men each. It had a single triangular sail on a long yard mounted at a 45° angle to the mast. The fleets also had smaller boats suitable for ferrying infantry and supplies on rivers.

Battle tactics
Roman battle tactics were a combination of naval engagement and infantry assault. The warships were equipped with a bronze-sheathed ram (rostrum) near sea level for puncturing the enemy hull, but “ramming speed” wasn’t the most important battle cry. The preferred method of attack was to land marines on the enemy deck and take the ship in hand-to-hand combat. After all, an enemy ship sunk brings glory, but an enemy ship taken brings glory and wealth.

The original boarding device, used at the time of the First Punic war, was a long plank (corvus) that could be lowered from the bow to drive a spike into the deck of the targeted ship. A switch to grappling hooks on a pole or chain let the crew draw up against the side of the enemy. The soldiers could then cross light ladders to the enemy deck.

A major advance was devised by Agrippa, commander of Augustus’s fleets. The harpax fired a grappling hook from a catapult, greatly increasing the range at which a ship could be snared.

Organization of the Roman Fleet
The navy was a less prestigious arm of the military, more analogous to the auxilia staffed by noncitizens commanded by equestrians than to the legions with their citizen soldiers and senatorial commanders.

The commander of each fleet was a prefect from the equestrian order, like the prefects who commanded the auxiliaries. The fleets were originally staffed with army officers. For a time under Claudius, the job was part of a civil career with some men having no real military experience. After this proved inadequate, Vespasian reorganized the navy and raised the status of its officers.

Prefect of the Misene Fleet was considered one of the most important equestrian posts and an excellent end to an illustrious career. Pliny the Elder held this post when Mount Vesuvius erupted. He took the fleet to rescue survivors, stayed to study the eruption, and died in the poisonous gases.

The posts of prefect of the fleet based at Misenum in the Bay of Naples or Ravenna on the northern Adriatic were administrative with little chance to see battle. Smaller provincial fleets were commanded by equestrian prefects and were equivalent to the command of an auxilia unit. In the 2nd century, the typical term of service for prefects was four to five years.

The lower ranking officers were based on the Greek model and had Greek names. The navarch (navarchus) was a squadron commander with 10 or so ships under his command. The triarch (triarchus) was a ship’s captain. These officers under Augustus were usually skilled Greek sailors. There were limited opportunities for advancement, and the navy was considered a lesser arm of the Roman military machine.

Crews were organized along Greek lines but with a Roman military command superimposed. Each ship had a small administrative staff under an older legionary on detached duty (a beneficiarius). In addition, a centurion and his second in command, the optio, were over the crew and the small force of infantry. The exact relationship in terms of rank and control between the triarch and centurion is not clear. All members of the crew were trained for battle, which presumably was directed by the centurion.

Rome and the rest of Italy had no great tradition of seafaring, so most of the sailors were from the provinces that engaged in maritime trade. Some were free men who were Roman citizens, but most were probably peregrines (not citizens of Rome). Egypt provided many sailors for the Roman warships. While commercial ships might have slave rowers, the Roman navy used free men who enlisted to serve the military goals of Rome, just like a legionary or auxiliary soldier.

The crew, rowers and otherwise, were recruited from the common people. Men enlisted in the navy for a 26-year term of service (one year more than an enlistee in a Roman auxiliary unit). Upon discharge, the sailor became a Roman citizen.

The crew of a warship included both sailors and a small force of trained infantry, much like today’s marines. The rowers and other crewmembers trained in the use of arms as well. In battle, the ship maneuvered close to the enemy ship to allow the infantry to board and fight to take over the enemy ship. Sometimes the crew also engaged the enemy.

When necessary, men from the navy could be transferred to bring a depleted legion to full strength. Nero, Vespasian, and Hadrian used the fleet as a source of warriors to replenish the I and II Adiutrix and the X Fretensis legions.


Adkins, Lesley and Roy A. Adkins. Handbook to Life in Ancient Rome. New York: Oxford University Press, 1998.

Webster, Graham. The Roman Imperial Army of the First and Second Centuries A.D. 3rd ed. Norman, OK: University of Oklahoma Press, 1985.

The Olympias trireme:
Video of sea trials in 1990:
Video on development and construction of trireme

Image of Roman bireme: By RamaOwn work, CC BY-SA 2.0 fr,

Images of Trajan’s column and “The Battle of Actium” and the map of Roman fleet locations in public domain.


Fact and Fiction by Carol Ashby