Sulla's attack on Rome or the battle of the Esquiline Forum (88 BC) was a key moment in the fall of the Roman Republic, and was the first time in at least 400 years that a Roman commander had led an army against the city (Sulla's First Civil War).
In 89 BC war finally broke out between Mithridates VI of Pontus and Rome, after a prolonged period of tension. Command of this war would be lucrative and prestigious, and L. Cornelius Sulla and Gaius Marius both wanted the command. Sulla was elected as one of the consuls of 88 BC, and was given the eastern command, but Marius formed an alliance with the Tribune Sulpicius, who was being frustrated in his attempts to gain a fairer deal for the newly enfranchised Italians, who had been made into Roman citizens as a result of the Italian Social War. Marius agreed to support Sulpicius in return for the eastern command. Sulpicius put forward a series of laws, which included the change of command and the voting reforms. Sulla responded by withdrawing to examine the heavens for omens, which stopped all public business. Sulpicius refused to accept this, and his supporters took to the streets to enforce their will. Sulla was forced to seek refuge with Marius (or chose to visit Marius for advice), and agreed to allow public business to resume. The laws passed, and officially command of the eastern war passed to Marius.
This was a dangerous moment, although it is clear that Marius and Sulpicius didn't realise just how dangerous. Sulla had already raised an army for the war against Mithridates (probably using troops he had commanded in the Social War), and this army was posted on the Via Appia, south of Rome. Appian places the army at Capua, while Plutarch, in his life of Sulla, has the advance begin at Nola. Sulla escaped from Rome and rushed to the army, where he quickly won over the troops. Appian describes the troops as being eager for the lucrative war against Mithridates and afraid that Marius would chose to use different troops. Sulla described the way he had been treated in Rome, and the army insisted that he should lead them to Rome. All but one of his senior officers disagreed, and fled back to Rome. One unnamed quaestor remained with him, and the general assumption is that this was Lucius Licinius Lucullus, one of the quaestors for the year, and an important officer under Sulla during the First Mithridatic War. Plutarch adds that the army killed the two military tribunes that Marius had sent to take command of the army.
Sulla now broke with all precedent, and led his army towards Rome. Marius, Sulpicius and the Senate send a series of delegations to the army to try and stop their advance. Plutarch reports that one was led by the praetors Brutus and Servilius, who were mistreated by the army, had their fasces broken and their senatorial togas stripped off them and were returned to Rome. Plutarch and Appian provide different versions of the final embassy. In Appian Sulla offered to meet with the Senate, Marius and Sulpicius on the Campus Martius, outside the city boundaries, where the two sides would consult. His fellow consul Quintus Pompeius Rufus meet him and offered his support. Marius and Sulpicius then asked Sulla to stop forty stades from the city while they prepared for the meeting. Sulla and Pompeius promised to obey this request, but had no intention of doing so. In Plutarch a deputation from the city reached Sulla with the news that the Senate had voted that Sulla should have all of his rights, and asking him not to advance beyond Picinae or Pictae, at some distance from the city. Again, Sulla agreed to camp, but didn't do so.
Both accounts now come together. Appian provides the most details. Sulla used one legion to seize the Esquiline gate, on the eastern side of the city (Plutarch has this advance led by Lucius Basillus and Caius Mummius, followed closely by Sulla). Pompeius with a second legion captured the Colline Gate, at the northern end of the city. A third legion captured the Pons Sublicius, or 'Wooden Bridge', over the Tiber. A fourth legion was left to watch the city walls. Sulla then led his remaining two legions into the city,
Appian and Plutarch agree on the first part of the battle. Angered by the presence of armed soldiers inside the sacred boundary of the city, the Roman people took to the roofs and pelted Basillus's men with tiles and stones, forcing them back to the walls. Sulla reached the fighting, and in a fit of anger ordered his men to set fire to the houses and use fire arrows against the civilian defenders of the city. This cleared the roofs, and Sulla was able to advance further into the city.
Marius and Sulpicius had managed to gather some troops of their own. They attacked Sulla's invaders near the Esquiline forum (probably located just inside the gate), in what Appian described as the first battle 'regularly fought in Rome with bugle and standards in full military fashion, no longer like a mere faction fight'. This suggests that Marius and Sulpicius had managed to at least find some veterans in the city. At first the defenders had the best of the fighting, and Sulla's men were wavering. Sulla seized a standard and led from the front to restore their morale. He then ordered reinforcements from the camp outside the city, and sent troops through the Suburra (to the south of the Esquiline hill) to attack Marius's men from the rear. This turned the tide of the battle. The Marians attempted to gain support by offering freedom to any slave who joined them (Plutarch places this call at the temple of Tellus, on the southern part of the Esquiline), and states that only three agreed to fight.
It was now clear that the battle was lost, and Marius fled from the city. After a series of adventures he reached safety in Africa, from where he prepared for his return. Sulpicius was less fortunate, and was captured and executed.
Sulla advanced to the Via Sacra, and he and Pompeius posted their troops throughout the city, remaining on watch themselves that night to prevent any disorders from breaking out. On the following day Sulla and Pompeius addressed the popular assembly, and proposed a series of changes to the constitution that Sulla hoped would reduce the danger of future civil strife.
However these measures failed. As soon as Sulla left Italy to take up the eastern command, his political arrangements in Rome collapsed. Lucius Cornelius Cinna, one of the consuls for 87 BC, attempted to undo Sulla's changes, but he was exiled after a massive outbreak of civil disorder. Cinna raised an army in Italy, and formed an alliance with Marius, who had raised a force of his own in Africa. In 87 BC the two men besieged and captured Rome, after a much longer struggle than in 88 BC, and the Marian faction controlled Italy until Sulla returned from the east in 83 BC (Sulla's Second Civil War).