Grain Supply To The City of Rome - Shipping and Milling

Shipping and Milling

The widespread use of water mills or grain crushers in Italy is mentioned in passing by Pliny the Elder in 79 AD. A sequence of water mills was established at the terminus of the highest Roman aqueduct, the Aqua Traiana in the second century AD by the emperor Trajan. Traces of the water channels and equipment have been excavated on the Janiculum. Protecting this valuable industrial complex was important, as attested by the actions of Belisarius in the Siege of Rome (537–538) when the city was besieged by the Ostrogoths. When the water supply to the aqueduct was cut off, he built a bridge of boats across the Tiber and used floating paddle mills to crush the grain, and so kept the supply of bread intact.

The complex of mills bear parallels with a similar complex at Barbegal in southern Gaul built in the first century AD, although the Barbegal mills have not been built upon at later times, and are thus extremely well preserved.

During the Principate, the surrounding Italian countryside only provided ten percent of the total grain imports into Rome. The majority of her grain came from North Africa and Egypt. Several assessments have been made toward the total amount of grain that Rome imported from these two regions. Peter Garnsey combines the accounts of the author of the fourth-century Epitome that 20 million modii of wheat came from Egypt and Josephus' statement in the mid-first century AD that North Africa provided twice the export of Egypt and that it supplied Rome eight months of the year and Egypt supplied the other four, leaving a total of 60 million modii imported to Rome. Garnsey finds this number too high as this works out to 400,000 tons but only 200,000 tonnes was required for Augustus' first grain dole. G.E. Rickman estimated that the total requirements of wheat for a population of Rome, given an average diet of 3,000 calories would require 40 million modii and using Josephus as his reference calculated 13 million modii imported from Egypt and 27 million modii imported from North Africa. An estimate in between these two numbers would probably be most accurate, as an excessive supply of imported grain would be desirable in case grain was lost at sea or spoiled in a warehouse. Grain would have also came from Sicily and Sardinia though these regions were not as important as they had been in the Republic after the annexation of Egypt by Augustus. A passage from Pliny also gives locations of grain exportation to Rome from Gaul, the Chersonese, Cyprus and Spain. These are not the only provinces to ship grain but were probably depended on the most.