The siege of Sutrium of 311/10-310/9 BC saw the first fighting in the brief Etruscan War of 311/10-308 BC, and saw the Etruscans fail in their attempt to capture this key border city.
Sutrium is just over thirty miles to the north-west of Rome, on one of the main routes between Rome and Etruria, and close to the edge of the Ciminian Forest, then a pathless wilderness that acted as a border between the Etruscans and the Romans.
The siege began in 311/10 BC (the first date comes from the tradition Roman chronology, which included a 'dictator year' in 309 that was probably fictional, thus the second date). The Etruscans had been preparing for war since the previous year, probably in an attempt to take advantage of Roman involvement in the Second Samnite War. The Romans responded by sending one of the consuls for 311 BC, Q. Aemilius Barbula, to lift the siege. His arrival triggered a debate in the Etruscan camp, and eventually they decided to risk a battle. Two days after Aemilius arrived at Sutrium the two armies formed up and fought a set-piece battle. According to Livy the Romans were outnumbered, although this may only refer to their first line troops.
The first part of the battle was equally balanced, with both sides suffering heavy losses. When the Romans brought up their second line the Etruscans were unable to respond, and were close to defeat when night came, ending the battle. Both sides had suffered heavy losses, but the Etruscans were able to continue the siege into the next year.
In 310/9 Aemilius was replaced by the new consul Quintus Fabius Maximus Rullianus. Both sides sent reinforcements to Sutrium, and the Romans were once again outnumbered.
Livy records two different possible ends to the siege. In both cases Fabius won a victory soon after reaching the city, and the Etruscans were forced back to their camp. The Romans then crossed the Ciminian forest and attacked the Etruscan heartland. The Etruscan's responded by raising a new larger army, but this too was defeated in battle. In Livy's main account this battle took place at Sutrium, and only then was the siege raised. However Livy reports a second tradition in which this battle took place at Perusia, on the far side of the forest. This defeat forced the Etruscans to abandon the siege of Sutrium. The important Etruscan cities of Perusia, Cortona and Arretium all withdrew from the war, after agreeing a thirty year truce with the Romans.