The siege of Bovianum (89 BC) was Sulla's last victory during his campaign of 89 BC, and saw him capture a Samnite town that was the site of the common council of the Italian rebels (Social War).
Sulla's campaign of 89 BC had started in Campania, where he had successfully besieged Pompeii and Herculanium, and defeated a Samnite relief effort (battle of Nola). He then moved east from Nola, and captured Aeclanum.
After the fall of Aeclanum Sulla accepted the submission of the Hirpini, in southern Samnium. His next aim was to move north-west into central Samnium, but Papius Mutilus, the senior Samnite commander, was guarding the main roads. Sulla outflanking him by taking a circuitous route and attacking from an unexpected direction. Papius Mutilus was defeated in a battle at an unknown location and Sulla sacked his camp. Papius Mutilus retreated to Aesernia, fifty-five miles to the north-west of Aeclanum.
Sulla's next target was Bovianum (modern Bojano), an important Samnite town forty miles to the north-west of Aesernia and fifteen to the south-east of Aesernia. Appian describes this as having three citadels, and being the site of the common council of the rebels. The original Italian capital had been further to the north, at Corfinium, but they had been forced to abandon this as the Romans overran the northern allies. Bovianum was their second known capital, but after Sulla captured the town they had to move again, this time to Aesernia.
The modern town is built on a plain to the north of a spur of the mountains, with the Civita Superiore on top of the peak nearest to the town. There are the remains of massive walls just to the west of this upper town, and plenty of possible locations on the nearby hills for the other two citadels.
Sulla's main camp must have been close to one of the three citadels. While the defenders watched Sulla's camp from one citadel, he sent a detachment to attack whichever of the other two was most vulnerable. Once they had captured one of the citadels they signalled their success with smoke. Sulla then launched a frontal assault, and after a battle that lasted for three hours captured the city. Bovianum was described as almost entirely depopulated by Strabo, suggesting that it had been sacked at some point during the war, either after Sulla's capture of the city or after the end of the fighting.
This was Sulla's last military success of the year. He then returned to Rome to stand for election as one of the Consuls for 88 BC. Sulla won his election, but the events of his first year as consul would cause as much damage to the Republic as the Social War. He was given the command of the war against Mithridates VI of Pontus (First Mithridatic War), but the command was then taken from him by Marius, with the aid of the tribune Sulpicius and mob violence. Sulla refused to accept his defeat and for the first time in centuries led a Roman army against the city (Sulla's First Civil War).
Bovianum probably didn't remain in Roman hands for long. Julius Obsequens, in his Book of Prodigies, reports that Poppaedius Silo held a triumph in Bovianum during the year of the consulship of Sulla and Quintus Pompeius Rufus (88 BC), but this was a bad omen, as a triumph was normally held in the conquering city, not the conquered city (in this case one could argue that Bovianum was actually both). Silo was killed in his next battle, the battle of the Teanus River (88 BC), probably fought around 45 miles to the north-east, on the border between Samnium and Apulia.