The Roman siege of Neapolis (Naples) of 327-326 BC was the first fighting in what developed into the Second Samnite War (327-304 BC).
Naples was a divided city in 328 BC. It had been founded by Greek settlers from Cumae, which had itself been founded by Chalcis in Euboea, and was now the last independent Greek in Campania. There were also a significant number of Oscan speakers in the city, given the Oscan speaking Samnites a foothold inside the walls. The events of the siege suggest that while the majority of the population supported the Samnites, and were opposed to Rome, some of the city's elite were pro-Roman.
By 327 BC at the latest Neapolis had begun to attack outlying Roman possessions in Campania, possibly with Samnite encouragement. The Senate responded by sending a delegation to Neapolis to demand compensation. The Neapolitan refused, and prepared for a siege. 2,000 troops from Nola and 4,000 from Samnium reached the city, and the Greek city of Tarantum promised to send ships.
The Romans sent the consul Q. Publilius Philo to attack Neapolis. Livy's account of the siege is somewhat distorted by his believe that Palaeopolis (the old city) and Neapolis (the new city) were two separate communities, rather than parts of a single city. He thus has Publilius camp between the two places, where he remained as his period in office came to an end.
The Roman Senate now made an important innovation that would play a major part in the success of the Republic. Instead of replacing Publilius he was made into a proconsul, extending his military authority into the following year. In future campaigns, as the Roman Republic expanded out of Italy, the ability to appoint proconsuls meant that a successful general could lead an entire campaign instead of being replaced after a year.
In this particular case the siege was ended by an internal dispute within the city. According to Livy the Neapolitans were increasingly repressed by the Samnite allies, until eventually they decided that the Romans were the lesser evil. It is now generally believed that while the majority of the population remained anti-Roman, a smaller group of aristocrats realised that Roman rule was probably the only way to retain their power.
Two of the leading men of the city, Charilaus and Nymphius, took the lead. Charilaus was sent out to the Roman camp to explain their plan, and to ask for good terms from Rome, while Nymphius was given the job of distracting the Samnites. He suggested that while the Romans were tied up around the walls the Samnite troops could use the Neapolitan fleet to raid the coast of Latium. The Samnites agreed, and most of them moved to the harbour. At this point Charilaus returned, with 3,000 Roman troops led by the military tribune L. Quinctius. His allies let him past the walls, and the Romans occupied the highest part of the city.
Very little fighting appears to have been needed. The Samnite troops were able to escape from the harbour area, although lost most of their possessions, while the contingent from Nola were able to leave the city at the opposite end to the Romans. Neapolis itself was well treated, becoming an ally of Rome.