The siege of Praeneste (82 BC) saw the consul Marius the Younger besieged in the city for most of the campaign of 82 BC, from his defeat at the battle of Sacriportus in the spring, to his suicide as the city surrendered to Sulla (Sulla's Second Civil War).
At the start of the campaign of 82 BC both sides split their efforts. Sulla sent Metellus Pius to try and gain control of Cisalpine Gaul, and the consul Carbo moved north to oppose him. In the south Sulla advanced towards Rome from Campania, while the consul Marius the Younger, son of the famous Gaius Marius, commanded the forces sent south from Rome to block him.
Marius's campaign didn't go well. He attempted to prevent the fall of Setia (Sezze), about 40 miles south of Rome, but failed. He then retreated north towards Signia (modern Segni), 13 miles to the north, but then decided to stop and fight. He suffered a heavy defeat at the battle of Sacriportus and had to flee towards Praeneste.
Sulla's men were close behind. The first refugees were let into the town, but the gates were then closed before Marius had arrived. He had to be hauled up the walls on the end of a rope, while more of his men were killed in fighting outside the walls. Sulla killed any Samnites who were captured, settling a grudge that could probably be traced back to the Social War and his First Civil War of 88-87 BC where they had sided against him.
Praeneste (modern Palestrina) sits on the lower slopes of a spur of the Apennines. To the west and south there is a gently undulating plain. The Alban Hills are to the south-west and the Lepini mountains are to the south.
Sulla now decided to starve out the defenders. He decided on the course for lines of circumvallation, and then left Q. Lucretius Ofella in charge of building the walls and conducting the siege. At first the defenders must have been able to get messages out of the town, as Marius was able to order L. Junius Brutus Damasippus, the city praetor, to kill a number of his opponents. His messengers arrived before Sulla's troops, and four of his senior opponents were murdered, two in the senate house. Soon after this Sulla was able to take Rome without a fight.
Sulla now concentrated his efforts against Carbo's army, which was based around Clusium, to the north of Rome. A series of engagements were fought in the area (ending with the first battle of Clusium and the battle of Spoletium), but neither side gained a significant advantage.
Carbo now made the first attempt to lift the siege. Gaius Marcius Censorinus was sent towards Praeneste with eight legions, but he was ambushed by Pompey while passing through a defile (sadly no location for this is given). Pompey defeated Marcius, and trapped the rest of his army on a hill. Pompey had already managed to let one of Carbo's lieutenants escape from him after Spoletium, and he repeated the trick now. Marcius escaped under the cover of darkness, leaving his camp fires burning to hide his movements. Although he managed to escape, his army dissolved after the escape. One legion moved north to Ariminum, which was at least still in Marian hands, but most of the other seven dispersed and he returned to Carbo's camp with only seven cohorts (3,500 men).
Carbo now gained the active support of the Samnites and Lucanians. A force of 70,000 men, under the Samnite Pontius Telesinus, the Lucanian Marcus Lamponius (a commander from the Social War) and Gutta from Capua (an otherwise entirely obscure figure), was approaching from the south, with the intention of lifting the siege of Praeneste (Telesinus's younger brother may have been amongst those inside the besieged city). This second attempt to lift the siege was no more successful than the first. According to Appian, Sulla moved to block the only pass leading to the city. This is rather problematic, as there is no obvious pass that would fit that description. The Samnites would probably have been coming from the south, so the gap between the Apennines and the Lepini mountains (part of the Lazio 'anti-Apennines') is one candidate. However the description could equally apply to the gap between the Alban Hills and the Lepini mountains or to any one of a series of passes in the Apennines to the east of the city (perhaps one that offered access to a weaker part of Sulla's walls of circumvallation in the difficult ground to the north-east of the city).
Wherever this pass was, Sulla was able to prevent the Samnites from reaching the city, and a second standoff developed at the pass. Back at Praeneste Marius made an active attempt to save himself. The walls of circumvallation were clearly some way from the city, as there was space for Marius to build a fort between the two sets of walls. He then used this as a base for a series of attempts to break through Ofella's siege lines. These all failed, and he withdrew back into the city.
In the meantime Carbo had attempted to take advantage of Sulla's absence to ambush Metellus Pius in his camp at Faventia, on the edge of Cisalpine Gaul, but the attack had gone disastrously wrong and most of his army had been destroyed. Carbo made one last attempt to save his position, sending two legions under L. Junius Brutus Damasippus to try and break through Sulla's blockade in the pass (quite why the Samnites or Damasippus couldn't have simply used one of the many other potential routes to Praeneste isn't explained in any of the sources. After the failure of this third relief effort, news arrived that Cisalpine Gaul had changed sides, and joined Sulla. This convinced Carbo that his cause was doomed, and he fled into exile in Africa.
The Marians still had as many as 100,000 men under arms in Italy (30,000 at Clusium, two legions under Damasippus and up to 70,000 Samnites and allies), but they were running out of leaders. Pompey inflicted a defeat on the 30,000 men at Clusium (second battle of Clusium, 82 BC), eliminating 20,000 of them. The remaining Marian leaders (Brutus Damasippus, Carinas and Marcius) made a fourth attempt to lift the siege, but this also failed.
The Samnites and the remaining Marians made one last attempt to win the war, by seizing Rome. They abandoned their camps at the mysterious pass, and marched on Rome. For once Sulla was caught out, and he had to rush back to Rome to try and save the city. He only just arrived in time, and the resulting battle of the Colline Gate was perhaps the closest Rome came to falling to a non-Roman foe in 800 years. Telesinus was killed during the battle. Lamponius escaped, but Marcius and Carinas were captured on the following day and executed.
Sulla sent the heads of Marcius and Carinas to be displayed outside Praeneste. This finally convinced the defenders of the city that their cause was hopeless and they agreed to surrender. Marius attempted to escape through some tunnels that led out of the city, but was trapped by men who had been posted outside the tunnels, and committed suicide (possibly by running onto the sword of Telesinus's younger brother, in a mutual suicide). His corpse was beheaded and his head was displayed in the forum. Ofella killed some of the senators who were captured in the city, and Sulla killed the rest of them. According to Appian Sulla then divided the captives into three - the Romans were pardoned, but the Praenestians and Samnites were all killed. The town then became a military colony. There is some evidence that not all of the Praenestians were killed. A military colony was then founded on the lands of Praeneste.