Roman navy
The naval forces of the ancient Roman state were instrumental in the Roman conquest of the Mediterranean Basin, but it never enjoyed the prestige of the Roman legions. 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 their ships. Because of that, the navy was never completely 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, and 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. By far, the navy's most vital task was to ensure Roman grain imports were shipped and delivered to the capital unimpeded across the Mediterranean. The navy also manned and maintained craft on major frontier rivers such as the Rhine and the Danube for supplying the army and preventing crossings by enemies.
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 Migration Period 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 with its capital at Carthage, 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 triremes, 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 praetores 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 quinqueremes 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 that 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 and Tyndaris 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 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 and the Ebro River, 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.