Roman sea-borne trading and the port of Ostia by Alison Morton

The Romans were organised, truly organised in complex ways not seen again until at least the 18th and 19th centuries. Trade was vital to Ancient Rome. The empire cost a vast sum of money to run and trade brought in much of that money. The population of the city of Rome grew to over one million and demand for more and different goods and services to build and maintain a high status lifestyle fuelled trade from further and further afield.

Roman trade routes map (ORBIS, Stanford Uni)

In addition to the 80,000 kilometres of first class roads (as at c. AD 200) built primarily for the movement of military forces, used by the imperial courier service, for government administration and lastly for trade, sea routes crossed the Empire through the Mediterranean from Spain, France and North Africa to Syria, north to Britannia and east to the Black Sea.  They supported trade between a network of coastal cities - Rome, Constantinople, Antioch, Alexandria, Carthage. These cities were serviced by a road network permitting trade within their respective hinterlands. River transport was not so widespread as the major pan-European rivers, the Rhine and the Danube, were military frontiers, not the core of the Empire.

The Romans built lighthouses, harbour complexes, docks and warehouses to further sea trade and make it secure. The Roman navy (classis) tried with varying success to keep the Mediterranean Sea safe from pirates. Although the navy was instrumental in the Roman conquest of the Mediterranean basin, it never enjoyed the prestige of the Roman legions. Romans were a primarily land-based people, and relied partially on other nationalities such as Greeks, Phoenicians 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". 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.

Trade was facilitated by a single official currency and no complicating customs dues. Trade developed in complexity and reach  as peace became more established and with more trade, prosperity increased. When the Empire disintegrated in the late AD 400s, overseas markets disappeared, supply and distribution routes became unsafe and trade collapsed. The Mediterranean Sea became a dangerous place for merchants as there were no powers to control the activities of pirates who marauded as far north as the English Channel.

What was acquired from where?
The Romans imported a whole variety of materials: beef, corn, glassware, iron, lead, leather, marble, olive oil, perfumes, purple dye, silk, silver, spices, timber, tin and wine. The main trading partners were in Spain, France, the Middle East and North Africa. Britain exported lead, woollen products and tin. In return, it imported from Rome wine, olive oil, pottery and papyrus.

Bireme (Creative Commons)

Ostia, Rome's port
The most important sea port was Ostia situated at the mouth of the River Tiber and only 15 miles from Rome. According to an inscription, the original castrum (military camp) of Ostia was established in the 7th century BC. However, the oldest archaeological remains so far discovered date back to only the 4th century BC when Rome fought several naval actions. 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. The most ancient buildings currently visible in Ostia are from the 3rd century BC, notably the castrum. From this point on, Ostia starts to play an important role as a military harbour. When Rome installed a new naval magistracy in 267 BC, one of the officials was permanently based in Ostia. Traders and artisans settled in Ostia to make a living in and around the harbour.

Goods could be quickly moved to Rome in barges up the River Tiber after slaves had unloaded and transferred cargo from merchant ships. The Romans built the world's first dual carriageway, via Portuensis, between Rome and Ostia. In 68 BC, the town was sacked by pirates. During the sack, the port was set on fire, the consular war fleet was destroyed, and two prominent senators kidnapped. This attack caused such panic in Rome that Pompey the Great arranged for the tribune Aulus Gabinius to propose a law, the Lex Gabinia, to allow Pompey to raise an army and destroy the pirates. Within a year, the pirates had been defeated.

Development
Ostia was further developed during the first century AD under the influence of Tiberius, who ordered the building of the town's first forum. Temples, bathhouses, a theatre, shops, warehouses, construction yards, workshops, guilds became an integral part of the town.

Ostia Antica forum (author photo)

With the expansion of the physical city and the demands of the population of Rome, traffic on the river became ever more congested. Manoeuvring became impossible on the 100 metre wide river and silting exacerbated the problem. To guarantee a consistent supply of corn for Rome, the emperor Claudius started to build a new harbour (portus) in 42 AD two miles north of Ostia on the northern mouths of the Tiber.

(ostia-antica.org)

Two curving moles were built out into the sea. Between the moles, on an island formed by sinking a large merchantman, a four-storied lighthouse was built. This harbour became silted up and around about 110 AD the emperor Trajan enlarged the new harbour with a huge land-locked inner hexagonal basin still visible today. Its form was hexagonal in order to reduce the erosive forces of the waves. The harbours were connected with the Tiber by canals.

Hexagonal basin (Uni Southampton)

The new Trajanic harbour was described as 'Portus Ostiensis' and the council and magistrates of Ostia also controlled the daily life of Portus. The harbours of Ostia continued their function as a major port as can be seen by traces of the many corn warehouses. This development took business away from Ostia itself which acted principally at that time as a river port only and began its commercial decline. One can only imagine the wrangling between the established guilds, merchants and city councillors in old Ostia and the up and coming traders of the modern, specifically designed new Portus.

Ostia and Portus grew to 50,000 inhabitants in the 2nd century, reaching a peak of some 100,000 inhabitants in the 2nd and 3rd centuries AD. Portus was critically important for supplying the ever-growing city of imperial Rome with foodstuffs and materials from across the Mediterranean.  It also acted as both a point of export for supplies and products from the Tiber Valley to the north of Rome, and a major hub for the redistribution of goods from ports across the Mediterranean. It must also have acted as a major conduit for people visiting Rome from around the Mediterranean.

Roman port litho, Seewesen by Walter Muller, 1893

Ostia was to play a major part in the downfall of Rome when Alaric the Goth captured it in AD 409 knowing that this would starve Rome of much needed food. The port began to enter a period of slow decline from the late 5th century AD onwards, although it was the scene of a major struggle between Byzantine and Ostrogothic troops during the Gothic wars (AD 535-553).

Ostia Antica chandler’s floor (author photo)

Today Ostia Antica in an outstanding site for tourists and students alike and noted for the excellent preservation of its ancient buildings, magnificent frescoes and impressive mosaics (http://www.ostia-antica.org).

Portus is the centre of an exciting project led by the University of Southampton (http://www.portusproject.org/). In 2014, a new canal and town wall at Ostia was discovered. In 2016, the Portus Project launched a series of online ‘tours’ https://tour.portusproject.org/en/about  (Click the menu bars at the top right to start).

I shall be following the project with great interest…

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Alison Morton is the author of the Roma Nova thriller series.
More at alison-morton.com