Roman navy The Roman navy ( , lit . " fleet " ) comprised the naval forces of the Ancient Roman state . The navy was instrumental in the Roman conquest of the Mediterranean basin , though it never enjoyed the prestige of the Roman legion s . Throughout their history , the Romans remained a primarily land - based people , and relied partially on their more nautically inclined subjects , such as the Greeks and the Egyptians , to build and man their ships . Partly because of this , the navy was never wholly embraced by the Roman state , and deemed somewhat " un - Roman " . In Antiquity , navies and trading fleets did not have the logistical autonomy that modern ships and fleets possess . Unlike modern naval forces , the Roman navy even at its height never existed as an autonomous service , but operated as an adjunct to the Roman army . During the course of the First Punic War , the Roman navy was massively expanded and played a vital role in the Roman victory and the Roman Republic ' s eventual ascension to hegemony in the Mediterranean Sea . In the course of the first half of the 2nd century BC , Rome went on to destroy Carthage and subdue the Hellenistic kingdoms of the eastern Mediterranean , achieving complete mastery of the inland sea , which they called " Mare Nostrum " . The Roman fleets were again prominent in the 1st century BC in the wars against the pirates , and in the civil wars that brought down the Republic , whose campaigns ranged across the Mediterranean . In 31 BC , the great naval Battle of Actium ended the civil wars culminating in the final victory of Augustus and the establishment of the Roman Empire . During the Imperial period , the Mediterranean became largely a peaceful " Roman lake " ; in the absence of a maritime enemy , the navy was reduced mostly to patrol , anti - piracy and transport duties . The navy also manned and maintained craft on major frontier rivers such as the Rhine and the Danube for supplying the army . On the fringes of the Empire , in new conquests or , increasingly , in defense against barbarian invasions , the Roman fleets were still engaged in open warfare . The decline of the Empire in the 3rd century took a heavy toll on the navy , which was reduced to a shadow of its former self , both in size and in combat ability . As successive waves of the " Völkerwanderung " crashed on the land frontiers of the battered Empire , the navy could only play a secondary role . In the early 5th century , the Roman frontiers were breached , and barbarian kingdoms appeared on the shores of the western Mediterranean . One of them , the Vandal Kingdom , raised a navy of its own and raided the shores of the Mediterranean , even sacking Rome , while the diminished Roman fleets were incapable of offering any resistance . The Western Roman Empire collapsed in the late 5th century . The navy of the surviving eastern Roman Empire is known as the Byzantine navy . History . Early Republic . The exact origins of the Roman fleet are obscure . A traditionally agricultural and land - based society , the Romans rarely ventured out to sea , unlike their Etruscan neighbours . There is evidence of Roman warships in the early 4th century BC , such as mention of a warship that carried an embassy to Delphi in 394 BC , but at any rate , the Roman fleet , if it existed , was negligible . The traditional birth date of the Roman navy is set at ca . 311 BC , when , after the conquest of Campania , two new officials , the " duumviri navales classis ornandae reficiendaeque causa " , were tasked with the maintenance of a fleet . As a result , the Republic acquired its first fleet , consisting of 20 ships , most likely trireme s , with each " duumvir " commanding a squadron of 10 ships . However , the Republic continued to rely mostly on her legions for expansion in Italy ; the navy was most likely geared towards combating piracy and lacked experience in naval warfare , being easily defeated in 282 BC by the Tarentines . This situation continued until the First Punic War : the main task of the Roman fleet was patrolling along the Italian coast and rivers , protecting seaborne trade from piracy . Whenever larger tasks had to be undertaken , such as the naval blockade of a besieged city , the Romans called on the allied Greek cities of southern Italy , the " socii navales " , to provide ships and crews . It is possible that the supervision of these maritime allies was one of the duties of the four new " praetor es classici " , who were established in 267 BC . First Punic War . The first Roman expedition outside mainland Italy was against the island of Sicily in 265 BC . This led to the outbreak of hostilities with Carthage , which would last until 241 BC . At the time , the Punic city was the unchallenged master of the western Mediterranean , possessing a long maritime and naval experience and a large fleet . Although Rome had relied on her legions for the conquest of Italy , operations in Sicily had to be supported by a fleet , and the ships available by Rome ' s allies were insufficient . Thus in 261 BC , the Roman Senate set out to construct a fleet of 100 quinquereme s and 20 triremes . According to Polybius , the Romans seized a shipwrecked Carthaginian quinquereme , and used it as a blueprint for their own ships . The new fleets were commanded by the annually elected Roman magistrates , but naval expertise was provided by the lower officers , who continued to be provided by the " socii " , mostly Greeks . This practice was continued until well into the Empire , something also attested by the direct adoption of numerous Greek naval terms . Despite the massive buildup , the Roman crews remained inferior in naval experience to the Carthaginians , and could not hope to match them in naval tactics , which required great maneuverability and experience . They therefore employed a novel weapon which transformed sea warfare to their advantage . They equipped their ships with the " corvus " , possibly developed earlier by the Syracusans against the Athenians . This was a long plank with a spike for hooking onto enemy ships . Using it as a boarding bridge , marines were able to board an enemy ship , transforming sea combat into a version of land combat , where the Roman legionaries had the upper hand . However , it is believed that the " corvus " ' weight made the ships unstable , and could capsize a ship in rough seas . Although the first sea engagement of the war , the Battle of the Lipari Islands in 260 BC , was a defeat for Rome , the forces involved were relatively small . Through the use of the " corvus " , the fledgling Roman navy under Gaius Duilius won its first major engagement later that year at the Battle of Mylae . During the course of the war , Rome continued to be victorious at sea : victories at Sulci ( 258 BC ) and Tyndaris ( 257 BC ) were followed by the massive Battle of Cape Ecnomus , where the Roman fleet under the consuls Marcus Atilius Regulus and Lucius Manlius inflicted a severe defeat on the Carthaginians . This string of successes allowed Rome to push the war further across the sea to Africa and Carthage itself . Continued Roman success also meant that their navy gained significant experience , although it also suffered a number of catastrophic losses due to storms , while conversely , the Carthaginian navy suffered from attrition . The Battle of Drepana in 249 BC resulted in the only major Carthaginian sea victory , forcing the Romans to equip a new fleet from donations by private citizens . In the last battle of the war , at Aegates Islands in 241 BC , the Romans under Gaius Lutatius Catulus displayed superior seamanship to the Carthaginians , notably using their rams rather than the now - abandoned " corvus " to achieve victory . Illyria and the Second Punic War . After the Roman victory , the balance of naval power in the Western Mediterranean had shifted from Carthage to Rome . This ensured Carthaginian acquiescence to the conquest of Sardinia and Corsica , and also enabled Rome to deal decisively with the threat posed by the Illyrian pirates in the Adriatic . The Illyrian Wars marked Rome ' s first involvement with the affairs of the Balkan peninsula . Initially , in 229 BC , a fleet of 200 warships was sent against Queen Teuta , and swiftly expelled the Illyrian garrisons from the Greek coastal cities of modern - day Albania . Ten years later , the Romans sent another expedition in the area against Demetrius of Pharos , who had rebuilt the Illyrian navy and engaged in piracy up into the Aegean . Demetrius was supported by Philip V of Macedon , who had grown anxious at the expansion of Roman power in Illyria . The Romans were again quickly victorious and expanded their Illyrian protectorate , but the beginning of the Second Punic War ( 218 – 201 BC ) forced them to divert their resources westwards for the next decades . Due to Rome ' s command of the seas , Hannibal , Carthage ' s great general , was forced to eschew a sea - borne invasion , instead choosing to bring the war over land to the Italian peninsula . Unlike the first war , the navy played little role on either side in this war . The only naval encounters occurred in the first years of the war , at Lilybaeum ( 218 BC ) and the Ebro River ( 217 BC ) , both resulting Roman victories . Despite an overall numerical parity , for the remainder of the war the Carthaginians did not seriously challenge Roman supremacy . The Roman fleet was hence engaged primarily with raiding the shores of Africa and guarding Italy , a task which included the interception of Carthaginian convoys of supplies and reinforcements for Hannibal ' s army , as well as keeping an eye on a potential intervention by Carthage ' s ally , Philip V . The only major action in which the Roman fleet was involved was the siege of Syracuse in 214 - 212 BC with 130 ships under Marcus Claudius Marcellus . The siege is remembered for the ingenious inventions of Archimedes , such as mirrors that burned ships or the so - called " Claw of Archimedes " , which kept the besieging army at bay for two years . A fleet of 160 vessels was assembled to support Scipio Africanus ' army in Africa in 202 BC , and , should his expedition fail , evacuate his men . In the event , Scipio achieved a decisive victory at Zama , and the subsequent peace stripped Carthage of its fleet . Operations in the East . Rome was now the undisputed mistress of the Western Mediterranean , and turned her gaze from defeated Carthage to the Hellenistic world . Small Roman forces had already been engaged in the First Macedonian War , when , in 214 BC , a fleet under Marcus Valerius Laevinus had successfully thwarted Philip V from invading Illyria with his newly built fleet . The rest of the war was carried out mostly by Rome ' s allies , the Aetolian League and later the Kingdom of Pergamon , but a combined Roman - Pergamene fleet of ca . 60 ships patrolled the Aegean until the war ' s end in 205 BC . In this conflict , Rome , still embroiled in the Punic War , was not interested in expanding her possessions , but rather in thwarting the growth of Philip ' s power in Greece . The war ended in an effective stalemate , and was renewed in 201 BC , when Philip V invaded Asia Minor . A naval battle off Chios ended in a costly victory for the Pergamene - Rhodian alliance , but the Macedonian fleet lost many warships , including its flagship , a " deceres " . Soon after , Pergamon and Rhodes appealed to Rome for help , and the Republic was drawn into the Second Macedonian War . In view of the massive Roman naval superiority , the war was fought on land , with the Macedonian fleet , already weakened at Chios , not daring to venture out of its anchorage at Demetrias . After the crushing Roman victory at Cynoscephalae , the terms imposed on Macedon were harsh , and included the complete disbandment of her navy . Almost immediately following the defeat of Macedon , Rome became embroiled in a war with the Seleucid Empire . This war too was decided mainly on land , although the combined Roman - Rhodian navy also achieved victories over the Seleucids at Myonessus and Eurymedon . These victories , which were invariably concluded with the imposition of peace treaties that prohibited the maintenance of anything but token naval forces , spelled the disappearance of the Hellenistic royal navies , leaving Rome and her allies unchallenged at sea . Coupled with the final destruction of Carthage , and the end of Macedon ' s independence , by the latter half of the 2nd century BC , Roman control over all of what was later to be dubbed " mare nostrum " ( " our sea " ) had been established . Subsequently , the Roman navy was drastically reduced , depending on its Greek allies to supply ships and crews as needed . Late Republic . Mithridates and the pirate threat . In the absence of a strong naval presence however , piracy flourished throughout the Mediterranean , especially in Cilicia , but also in Crete and other places , further reinforced by money and warships supplied by King Mithridates VI of Pontus , who hoped to enlist their aid in his wars against Rome . In the First Mithridatic War ( 89 – 85 BC ) , Sulla had to requisition ships wherever he could find them to counter Mithridates ' fleet . Despite the makeshift nature of the Roman fleet however , in 86 BC Lucullus defeated the Pontic navy at Tenedos . Immediately after the end of the war , a permanent force of ca . 100 vessels was established in the Aegean from the contributions of Rome ' s allied maritime states . Although sufficient to guard against Mithridates , this force was totally inadequate against the pirates , whose power grew rapidly . Over the next decade , the pirates defeated several Roman commanders , and raided unhindered even to the shores of Italy , reaching Rome ' s harbor , Ostia . According to the account of Plutarch , " the ships of the pirates numbered more than a thousand , and the cities captured by them four hundred . " Their activity posed a growing threat for the Roman economy , and a challenge to Roman power : several prominent Romans , including two praetor s with their retinue and the young Julius Caesar , were captured and held for ransom . Perhaps most important of all , the pirates disrupted Rome ' s vital lifeline , namely the massive shipments of grain and other produce from Africa and Egypt that were needed to sustain the city ' s population . The resulting grain shortages were a major political issue , and popular discontent threatened to become explosive . In 74 BC , with the outbreak of the Third Mithridatic War , Marcus Antonius ( the father of Mark Antony ) was appointed " praetor " with extraordinary " imperium " against the pirate threat , but signally failed in his task : he was defeated off Crete in 72 BC , and died shortly after . Finally , in 67 BC the " Lex Gabinia " was passed in the Plebeian Council , vesting Pompey with unprecedented powers and authorizing him to move against them . In a massive and concerted campaign , Pompey cleared the seas from the pirates in only three months . Afterwards , the fleet was reduced again to policing duties against intermittent piracy . Caesar and the Civil Wars . In 56 BC , for the first time a Roman fleet engaged in battle outside the Mediterranean . This occurred during Julius Caesar ' s Gallic Wars , when the maritime tribe of the Veneti rebelled against Rome . Against the Veneti , the Romans were at a disadvantage , since they did not know the coast , and were inexperienced in fighting in the open sea with its tides and currents . Furthermore , the Veneti ships were superior to the light Roman galleys . They were built of oak and had no oars , being thus more resistant to ramming . In addition , their greater height gave them an advantage in both missile exchanges and boarding actions . In the event , when the two fleets encountered each other in Quiberon Bay , Caesar ' s navy , under the command of D . Brutus , resorted to the use of hooks on long poles , which cut the halyard s supporting the Veneti sails . Immobile , the Veneti ships were easy prey for the legionaries who boarded them , and fleeing Veneti ships were taken when they became becalmed by a sudden lack of winds . Having thus established his control of the English Channel , in the next years Caesar used this newly built fleet to carry out two invasions of Britain . The last major campaigns of the Roman navy in the Mediterranean until the late 3rd century AD would be in the civil wars that ended the Republic . In the East , the Republican faction quickly established its control , and Rhodes , the last independent maritime power in the Aegean , was subdued by Gaius Cassius Longinus in 43 BC , after its fleet was defeated off Kos . In the West , against the triumvirs stood Sextus Pompeius , who had been given command of the Italian fleet by the Senate in 43 BC . He took control of Sicily and made it his base , blockading Italy and stopping the politically crucial supply of grain from Africa to Rome . After suffering a defeat from Sextus in 42 BC , Octavian initiated massive naval armaments , aided by his closest associate , Marcus Agrippa : ships were built at Ravenna and Ostia , the new artificial harbor of Portus Julius built at Cumae , and soldiers and rowers levied , including over 20 , 000 manumitted slaves . Finally , Octavian and Agrippa defeated Sextus in the Battle of Naulochus in 36 BC , putting an end to all Pompeian resistance . Octavian ' s power was further enhanced after his victory against the combined fleets of Mark Antony and Cleopatra , Queen of Egypt , in the Battle of Actium in 31 BC , where Antony had assembled 500 ships against Octavian ' s 400 ships . This last naval battle of the Roman Republic definitively established Octavian as the sole ruler over Rome and the Mediterranean world . In the aftermath of his victory , he formalized the Fleet ' s structure , establishing several key harbors in the Mediterranean ( see below ) . The now fully professional navy had its main duties consist of protecting against piracy , escorting troops and patrolling the river frontiers of Europe . It remained however engaged in active warfare in the periphery of the Empire . Principate . Operations under Augustus . Under Augustus and after the conquest of Egypt there were increasing demands from the Roman economy to extend the trade lanes to India . The Arabian control of all sea routes to India was an obstacle . One of the first naval operations under " princeps " Augustus was therefore the preparation for a campaign on the Arabian Peninsula . Aelius Gallus , the prefect of Egypt ordered the construction of 130 transports and subsequently carried 10 , 000 soldiers to Arabia . But the following march through the desert towards Yemen failed and the plans for control of the Arabian peninsula had to be abandoned . At the other end of the Empire , in Germania , the navy played an important role in the supply and transport of the legion s . In 15 BC an independent fleet was installed at the Lake Constance . Later , the generals Drusus and Tiberius used the Navy extensively , when they tried to extend the Roman frontier to the Elbe . In 12 BC Drusus ordered the construction of a fleet of 1 , 000 ships and sailed them along the Rhine into the North Sea . The Frisii and Chauci had nothing to oppose the superior numbers , tactics and technology of the Romans . When these entered the river mouths of Weser and Ems , the local tribes had to surrender . In 5 BC the Roman knowledge concerning the North and Baltic Sea was fairly extended during a campaign by Tiberius , reaching as far as the Elbe : Plinius describes how Roman naval formations came past Heligoland and set sail to the north - eastern coast of Denmark , and Augustus himself boasts in his " Res Gestae " : " My fleet sailed from the mouth of the Rhine eastward as far as the lands of the Cimbri to which , up to that time , no Roman had ever penetrated either by land or by sea . . . " . The multiple naval operations north of Germania had to be abandoned after the battle of the Teutoburg Forest in the year 9 AD . Julio - Claudian dynasty . In the years 15 and 16 , Germanicus carried out several fleet operations along the rivers Rhine and Ems , without permanent results due to grim Germanic resistance and a disastrous storm . By 28 , the Romans lost further control of the Rhine mouth in a succession of Frisian insurgencies . From 43 to 85 , the Roman navy played an important role in the Roman conquest of Britain . The " classis Germanica " rendered outstanding services in multitudinous landing operations . In 46 , a naval expedition made a push deep into the Black Sea region and even travelled on the Tanais . In 47 a revolt by the Chauci , who took to piratical activities along the Gallic coast , was subdued by Gnaeus Domitius Corbulo . By 57 an expeditionary corps reached Chersonesos ( see Charax , Crimea ) . It seems that under Nero , the navy obtained strategically important positions for trading with India ; but there was no known fleet in the Red Sea . Possibly , parts of the Alexandrian fleet were operating as escorts for the Indian trade . In the Jewish revolt , from 66 to 70 , the Romans were forced to fight Jewish ships , operating from a harbour in the area of modern Tel Aviv , on Israel ' s Mediterranean coast . In the meantime several flotilla engagements on the Sea of Galilee took place . In 68 , as his reign became increasingly insecure , Nero raised " legio " I " Adiutrix " from sailors of the praetorian fleets . After Nero ' s overthrow , in 69 , the " Year of the four emperors " , the praetorian fleets supported Emperor Otho against the usurper Vitellius , and after his eventual victory , Vespasian formed another legion , " legio " II " Adiutrix " , from their ranks . Only in the Pontus did Anicetus , the commander of the " Classis Pontica " , support Vitellius . He burned the fleet , and sought refuge with the Iberian tribes , engaging in piracy . After a new fleet was built , this revolt was subdued . Flavian , Antonine and Severan dynasties . During the Batavian rebellion of Gaius Julius Civilis ( 69 - 70 ) , the rebels got hold of a squadron of the Rhine fleet by treachery , and the conflict featured frequent use of the Roman Rhine flotilla . In the last phase of the war , the British fleet and " legio " XIV were brought in from Britain to attack the Batavian coast , but the Cananefates , allies of the Batavians , were able to destroy or capture a large part of the fleet . In the meantime , the new Roman commander , Quintus Petillius Cerialis , advanced north and constructed a new fleet . Civilis attempted only a short encounter with his own fleet , but could not hinder the superior Roman force from landing , Adventuring and ravaging the island of the Batavians , leading to the negotiation of a peace soon after . In the years 82 to 85 , the Romans under Gnaeus Julius Agricola launched a campaign against the Caledonians in modern Scotland . In this context the Roman navy significantly escalated activities on the eastern Scottish coast . Simultaneously multiple expeditions and reconnaissance trips were launched . During these the Romans would capture the Orkney Islands ( " Orcades " ) for a short period of time and obtained information about the Shetland Islands . There is some speculation about a Roman landing in Ireland , based on Tacitus reports about Agricola contemplating the island ' s conquest , but no conclusive evidence to support this theory has been found . Under the Five Good Emperors the navy operated mainly on the rivers ; so it played an important role during Trajan ' s conquest of Dacia and temporarily an independent fleet for the Euphrates and Tigris rivers was founded . Also during the wars against the Marcomanni confederation under Marcus Aurelius several combats took place on the Danube and the Tisza . Under the aegis of the Severan dynasty , the only known military operations of the navy were carried out under Septimius Severus , using naval assistance on his campaigns along the Euphrates and Tigris , as well as in Scotland . Thereby Roman ships reached " inter alia " the Persian Gulf and the top of the British Isles . 3rd century crisis . As the 3rd century dawned , the Roman Empire was at its peak . In the Mediterranean , peace had reigned for over two centuries , as piracy had been wiped out and no outside naval threats occurred . As a result , complacency had set in : naval tactics and technology were neglected , and the Roman naval system had become moribund . After 230 however and for fifty years , the situation changed dramatically . The so - called " Crisis of the Third Century " ushered a period of internal turmoil , and the same period saw a renewed series of seaborne assaults , which the imperial fleets proved unable to stem . In the West , Picts and Irish ships raided Britain , while the Saxons raided the North Sea , forcing the Romans to abandon Frisia . In the East , the Goths and other tribes from modern Ukraine raided in great numbers over the Black Sea . These invasions began during the rule of Trebonianus Gallus , when for the first time Germanic tribes built up their own powerful fleet in the Black Sea . Via two surprise attacks ( 256 ) on Roman naval bases in the Caucasus and near the Danube , numerous ships fell into the hands of the Germans , whereupon the raids were extended as far as the Aegean Sea ; Byzantium , Athens , Sparta and other towns were plundered and the responsible provincial fleets were heavily debilitated . It was not until the attackers made a tactical error , that their onrush could be stopped . In 267 – 270 another , much fiercer series of attacks took place . A fleet composed of Heruli and other tribes raided the coasts of Thrace and the Pontus . Defeated off Byzantium by general Venerianus , the barbarians fled into the Aegean , and ravaged many islands and coastal cities , including Athens and Corinth . As they retreated northwards over land , they were defeated by Emperor Gallienus at Nestos . However , this was merely the prelude to an even larger invasion that was launched in 268 / 269 : several tribes banded together ( the " Historia Augusta " mentions Scythians , Greuthungi , Tervingi , Gepids , Peucini , Celts and Heruli ) and allegedly 2 , 000 ships and 325 , 000 men strong , raided the Thracian shore , attacked Byzantium and continued raiding the Aegean as far as Crete , while the main force approached Thessalonica . Emperor Claudius II however was able to defeat them at the Battle of Naissus , ending the Gothic threat for the time being . Barbarian raids also increased along the Rhine frontier and in the North Sea . Eutropius mentions that during the 280s , the sea along the coasts of the provinces of Belgica and Armorica was " infested with Franks and Saxons " . To counter them , Maximian appointed Carausius as commander of the British Fleet . However , Carausius rose up in late 286 and seceded from the Empire with Britannia and parts of the northern Gallic coast . With a single blow Roman control of the channel and the North Sea was lost , and emperor Maximinus was forced to create a completely new Northern Fleet , but in lack of training it was almost immediately destroyed in a storm . Only in 293 , under " Caesar " Constantius Chlorus did Rome regain the Gallic coast . A new fleet was constructed in order to cross the Channel , and in 296 , with a concentric attack on Londinium the insurgent province was retaken . Late Antiquity . By the end of the 3rd century , the Roman navy had declined dramatically . Although Emperor Diocletian is held to have strengthened the navy , and increased its manpower from 46 , 000 to 64 , 000 men , the old standing fleets had all but vanished , and in the civil wars that ended the Tetrarchy , the opposing sides had to mobilize the resources and commandeered the ships of the Eastern Mediterranean port cities . These conflicts thus brought about a renewal of naval activity , culminating in the Battle of the Hellespont in 324 between the forces of Constantine I under Caesar Crispus and the fleet of Licinius , which was the only major naval confrontation of the 4th century . Vegetius , writing at the end of the 4th century , testifies to the disappearance of the old praetorian fleets in Italy , but comments on the continued activity of the Danube fleet . In the 5th century , only the eastern half of the Empire could field an effective fleet , as it could draw upon the maritime resources of Greece and the Levant . Although the " Notitia Dignitatum " still mentions several naval units for the Western Empire , these were apparently too depleted to be able to carry out much more than patrol duties . At any rate , the rise of the naval power of the Vandal Kingdom under Geiseric in North Africa , and its raids in the Western Mediterranean , were practically uncontested . Although there is some evidence of West Roman naval activity in the first half of the 5th century , this is mostly confined to troop transports and minor landing operations . The historian Priscus and Sidonius Apollinaris affirm in their writings that by the mid - 5th century , the Western Empire essentially lacked a war navy . Matters became even worse after the disastrous failure of the fleets mobilized against the Vandals in 460 and 468 , under the emperors Majorian and Anthemius . For the West , there would be no recovery , as the last Western Emperor , Romulus Augustulus , was deposed in 476 . In the East however , the classical naval tradition survived , and in the 6th century , a standing navy was reformed . The East Roman ( Byzantine ) navy would remain a formidable force in the Mediterranean until the 11th century . Organization . Crews . The bulk of a galley ' s crew was formed by the rowers , the " remiges " ( sing . " remex " ) or " eretai " ( sing . " eretēs " ) in Greek . Despite popular perceptions , the Roman fleet , and ancient fleets in general , relied throughout their existence on rowers of free status , and not on galley slave s . Slaves were employed only in times of pressing manpower demands or extreme emergency , and even then , they were freed first . In Imperial times , non - citizen freeborn provincials ( " peregrini " ) , chiefly from nations with a maritime background such as Greeks , Phoenicians , Syrians and Egyptians , formed the bulk of the fleets ' crews . During the early Principate , a ship ' s crew , regardless of its size , was organized as a " centuria " . Crewmen could sign on as marines , rowers / seamen , craftsmen and various other jobs , though all personnel serving in the imperial fleet were classed as " milites " ( " soldiers " ) , regardless of their function ; only when differentiation with the army was required , were the adjectives " classiarius " or " classicus " added . Along with several other instances of prevalence of army terminology , this testifies to the lower social status of naval personnel , considered inferior to the auxiliaries and the legionaries . Emperor Claudius first gave legal privileges to the navy ' s crewmen , enabling them to receive Roman citizenship after their period of service . This period was initially set at a minimum of 26 years ( one year more than the legions ) , and was later expanded to 28 . Upon honorable discharge ( " honesta missio " ) , the sailors received a sizable cash payment as well . As in the army , the ship ' s " centuria " was headed by a centurion with an " optio " as his deputy , while a " beneficiarius " supervised a small administrative staff . Among the crew were also a number of " principales " ( junior officers ) and " immunes " ( specialists exempt from certain duties ) . Some of these positions , mostly administrative , were identical to those of the army auxiliaries , while some ( mostly of Greek provenance ) were peculiar to the fleet . An inscription from the island of Cos , dated to the First Mithridatic War , provides us with a list of a ship ' s officers , the " nautae " : the " gubernator " ( " kybernētēs " in Greek ) was the helmsman or pilot , the " celeusta " ( " keleustēs " in Greek ) supervised the rowers , a " proreta " ( " prōreus " in Greek ) was the look - out stationed at the bow , a " pentacontarchos " was apparently a junior officer , and an " iatros " ( Lat . " medicus " ) , the ship ' s doctor . Each ship was commanded by a " trierarch us " , whose exact relationship with the ship ' s centurion is unclear . Squadrons , most likely of ten ships each , were put under a " nauarchus " , who often appears to have risen from the ranks of the " trierarchi " . The post of " nauarchus archigubernes " or " nauarchus princeps " appeared later in the Imperial period , and functioned either as a commander of several squadrons or as an executive officer under a civilian admiral , equivalent to the legionary " primus pilus " . All these were professional officers , usually " peregrini " , who had a status equal to an auxiliary centurion ( and were thus increasingly called " centuriones [ classiarii ] " after ca . 70 AD ) . Until the reign of Antoninus Pius , their careers were restricted to the fleet . Only in the 3rd century were these officers equated to the legionary centurions in status and pay , and could henceforth be transferred to a similar position in the legions . High Command . During the Republic , command of a fleet was given to a serving magistrate or promagistrate , usually of consular or praetor ian rank . In the Punic Wars for instance , one consul would usually command the fleet , and another the army . In the subsequent wars in the Eastern Mediterranean , praetors would assume the command of the fleet . However , since these men were political appointees , the actual handling of the fleets and of separate squadrons was entrusted to their more experienced legates and subordinates . It was therefore during the Punic Wars that the separate position of " praefectus classis " ( " fleet prefect " ) first appeared . Initially subordinate to the magistrate in command , after the fleet ' s reorganization by Augustus , the " praefectus classis " became a procurator ial position in charge of each of the permanent fleets . These posts were initially filled either from among the equestrian class , or , especially under Claudius , from the Emperor ' s freedmen , thus securing imperial control over the fleets . From the period of the Flavian emperors , the status of the " praefectura " was raised , and only equestrians with military experience who had gone through the " militia equestri " were appointed . Nevertheless , the prefects remained largely political appointees , and despite their military experience , usually in command of army auxiliary units , their knowledge of naval matters was minimal , forcing them to rely on their professional subordinates . The difference in importance of the fleets they commanded was also reflected by the rank and the corresponding pay of the commanders . The prefects of the two praetorian fleets were ranked " procuratores ducenarii " , meaning they earned 200 , 000 sesterces annually , the prefects of the " Classis Germanica " , the " Classis Britannica " and later the " Classis Pontica " were " centenarii " ( i . e . earning 100 , 000 sesterces ) , while the other fleet prefects were " sexagenarii " ( i . e . they received 60 , 000 sesterces ) . Ship types . The generic Roman term for an oar - driven galley warship was " long ship " ( Latin : " navis longa " , Greek : " naus makra " ) , as opposed to the sail - driven " navis oneraria " , a merchant vessel , or the minor craft ( " navigia minora " ) like the " scapha " . The navy consisted of a wide variety of different classes of warships , from heavy polyremes to light raiding and scouting vessels . Unlike the rich Hellenistic Successor kingdoms in the East however , the Romans did not rely on heavy warships , with quinquereme s ( Gk . " pentērēs " ) , and to a lesser extent quadrireme s ( Gk . " tetrērēs " ) and trireme s ( Gk . " triērēs " ) providing the mainstay of the Roman fleets from the Punic Wars to the end of the Civil Wars . The heaviest vessel mentioned in Roman fleets during this period was the hexareme , of which a few were used as flagships . Lighter vessels such as the liburnians and the hemiolia , both swift types invented by pirates , were also adopted as scouts and light transport vessels . During the final confrontation between Octavian and Mark Antony , Octavian ' s fleet was composed of quinqueremes , together with some " sixes " and many triremes and liburnians , while Antony , who had the resources of Ptolemaic Egypt to draw upon , fielded a fleet also mostly composed of quinqueremes , but with a sizeable complement of heavier warships , ranging from " sixes " to " tens " ( Gk . " dekērēs " ) . Later historical tradition made much of the prevalence of lighter and swifter vessels in Octavian ' s fleet , with Vegetius even explicitly ascribing Octavian ' s victory to the liburnians . This prominence of lighter craft in the historical narrative is perhaps best explained in light of subsequent developments . After Actium , the operational landscape had changed : for the remainder of the Principate , no opponent existed to challenge Roman naval hegemony , and no massed naval confrontation was likely . The tasks at hand for the Roman navy were now the policing of the Mediterranean waterways and the border rivers , suppression of piracy , and escort duties for the grain shipments to Rome and for imperial army expeditions . Lighter ships were far better suited to these tasks , and after the reorganization of the fleet following Actium , the largest ship kept in service was a hexareme , the flagship of the " Classis Misenensis " . The bulk of the fleets was composed of the lighter triremes and liburnians ( Latin : " liburna " , Greek : " libyrnis " ) , with the latter apparently providing the majority of the provincial fleets . In time , the term " liburnian " came to mean " warship " in a generic sense . In addition , there were smaller oared vessels , such as the " navis actuaria " , with 30 oars ( 15 on each bank ) , a ship primarily used for transport in coastal and fluvial operations , for which its shallow draught and flat keel were ideal . In late Antiquity , it was succeeded in this role by the " navis lusoria " ( " playful ship " ) , which was extensively used for patrols and raids by the legionary flotillas in the Rhine and Danube frontiers . Roman ships were commonly named after gods ( " Mars " , " Iuppiter " , " Minerva " , " Isis " ) , mythological heroes ( " Hercules " ) , geographical maritime features such as " Rhenus " or " Oceanus " , concepts such as Harmony , Peace , Loyalty , Victory ( " Concordia " , " Pax " , " Fides " , " Victoria " ) or after important events ( " Dacicus " for the Trajan ' s Dacian Wars or " Salamina " for the Battle of Salamis ) . They were distinguished by their figurehead ( " insigne " or " parasemum " ) , and , during the Civil Wars at least , by the paint schemes on their turrets , which varied according to each fleet . Armament and tactics . In Classical Antiquity , a ship ' s main weapon was the ram ( " rostra " , hence the name " navis rostrata " for a warship ) , which was used to sink or immobilize an enemy ship by holing its hull . Its use , however , required a skilled and experienced crew and a fast and agile ship like a trireme or quinquereme . In the Hellenistic period , the larger navies came instead to rely on greater vessels . This had several advantages : the heavier and sturdier construction lessened the effects of ramming , and the greater space and stability of the vessels allowed the transport not only of more marines , but also the placement of deck - mounted ballista e and catapult s . Although the ram continued to be a standard feature of all warships and ramming the standard mode of attack , these developments transformed the role of a warship : from the old " manned missile " , designed to sink enemy ships , they became mobile artillery platforms , which engaged in missile exchange and boarding actions . The Romans in particular , being initially inexperienced at sea combat , relied upon boarding actions through the use of the " corvus " . Although it brought them some decisive victories , it was discontinued because it tended to unbalance the quinqueremes in high seas ; two Roman fleets are recorded to have been lost during storms in the First Punic War . During the Civil Wars , a number of technical innovations , which are attributed to Agrippa , took place : the " harpax " , a catapult - fired grappling hook , which was used to clamp onto an enemy ship , reel it in and board it , in a much more efficient way than with the old " corvus " , and the use of collapsible fighting towers placed one apiece bow and stern , which were used to provide the boarders with supporting fire . Fleets . Principate period . After the end of the civil wars , Augustus reduced and reorganized the Roman armed forces , including the navy . A large part of the fleet of Mark Antony was burned , and the rest was withdrawn to a new base at Forum Iulii ( modern Fréjus ) , which remained operative until the reign of Claudius . However , the bulk of the fleet was soon subdivided into two praetorian fleets at Misenum and Ravenna , supplemented by a growing number of minor ones in the provinces , which were often created on an " ad hoc " basis for specific campaigns . This organizational structure was maintained almost unchanged until the 4th century . Praetorian fleets . The two major fleets were stationed in Italy and acted as a central naval reserve , directly available to the Emperor ( hence the designation " praetorian " ) . In the absence of any naval threat , their duties mostly involved patrolling and transport duties . These were not confined to the waters around Italy , but throughout the Mediterranean . There is epigraphic evidence for the presence of sailors of the two praetorian fleets at Piraeus and Syria . These two fleets were : Provincial fleets . The various provincial fleets were smaller than the praetorian fleets and composed mostly of lighter vessels . Nevertheless , it was these fleets that saw action , in full campaigns or raids on the periphery of the Empire . In addition , there is significant archaeological evidence for naval activity by certain legions , which in all likelihood operated their own squadrons : " legio " XXII " Primigenia " in the Upper Rhine and Main rivers , " legio " X " Fretensis " in the Jordan River and the Sea of Galilee , and several legionary squadrons in the Danube frontier . Dominate period . Our main source for the structure of the late Roman military is the " Notitia Dignitatum " , which corresponds to the situation of the 390s for the Eastern Empire and the 420s for the Western Empire . Notable in the " Notitia " is the large number of smaller squadrons that have been created , most of these fluvial and of a local operational role . Fleets of the Danube frontier . The " Classis Pannonica " and the " Classis Moesica " were broken up into several smaller squadrons , collectively termed " Classis Histrica " , authority of the frontier commanders ( " duces " ) . with bases at Mursa in Pannonia II , Florentia in Pannonia Valeria , Arruntum in Pannonia I , Viminacium in Moesia I and Aegetae in Dacia ripensis . Smaller fleets are also attested on the tributaries of the Danube : the " Classis Arlapensis et Maginensis " ( based at Arelape and Comagena ) and the " Classis Lauriacensis " ( based at Lauriacum ) in Pannonia I , the " Classis Stradensis et Germensis " , based at Margo in Moesia I , and the " Classis Ratianensis " , in Dacia ripensis . The naval units were complemented by port garrisons and marine units , drawn from the army . In the Danube frontier these were : Fleets in Western Europe . In the West , and in particular in Gaul , several fluvial fleets had been established . These came under the command of the " magister peditum " of the West , and were : It is notable that , with the exception of the praetorian fleets ( whose retention in the list does not necessarily signify an active status ) , the old fleets of the Principate are missing . The " Classis Britannica " vanishes under that name after the mid - 3rd century ; its remnants were later subsumed in the Saxon Shore system . By the time of the " Notitia Dignitatum " , the " Classis Germanica " has ceased to exist ( it is last mentioned under Julian in 359 ) , most probably due to the collapse of the Rhine frontier after the Crossing of the Rhine by the barbarians in winter 405 - 406 , and the Mauretanian and African fleets had been disbanded or taken over by the Vandals . Fleets in the Eastern Mediterranean . As far as the East is concerned , we know from legal sources that the " Classis Alexandrina " and the " Classis Seleucena " continued to operate , and that in ca . 400 a " Classis Carpathia " was detached from the Syrian fleet and based at the Aegean island of Karpathos . A fleet is known to have been stationed at Constantinople itself , but no further details are known about it . Ports . Major Roman ports were :