Portus Julius

Portus Julius was the first harbour specifically constructed to be a base for the Roman western naval fleet, the classis Misenensis [1]. The port was located near Baiae and protected by the Misenum peninsula at the north-western end of the Gulf of Naples [1]. During the civil wars from 39 BC after the Pact of Misenum, Octavian urgently needed a safe naval harbour in which to build and train a fleet for a campaign against Sextus Pompeius who was making frequent raids on Italy and upon the shipping routes for Rome's grain supply [1]. Agrippa's plan, executed from 37–36 BC, was to dig a canal to connect Lake Avernus to Lucrinus Lacus (Lake Lucrino) and a second, shorter canal with a hidden entrance between Lake Lucrino and the sea [1]. Shortly after the successful conclusion of the war with Sextus, the first Portus was abandoned, owing to accumulations of silt that compromised its navigability [1]. At the end of the fifth century the breakwater of Portus Iulius became submerged due to Bradyseism [1].