Bellum Octavianum

The Social War (from Latin bellum sociale, "war of the allies"), also called the Italian War or the Marsic War, was fought largely from 91 to 88 BC between the Roman Republic and several of its autonomous allies (socii) in Italy. Some of the allies held out until 87 BC.

The war started in late 91 BC, with the rebellion of Asculum. Other Italian towns quickly declared for the rebels and the Roman response was initially confused. By the new year, the Romans had levied huge armies to crush the rebels but found initial headway difficult. By the end of the year, however, they were able to cut the Italian rebels into two, isolating them into northern and southern sectors. The Italian rebels attempted to invade Etruria and Umbria at the start of 89 BC but were defeated. In the south, they were defeated by Lucius Cornelius Sulla, who for his victories would win a consulship the next year. The Romans retained the initiative and by 88 BC, the conflict was largely over and Roman attention had been captured by the ongoing First Mithridatic War. The few Italian rebels on the field by 87 BC eventually reached a negotiated settlement during a short civil war that year. At various stages of the war, Romans brought legislation allowing Italian towns to elect Roman citizenship if they had not revolted or would otherwise put down arms, draining support from the rebels.

Lucius Cornelius Cinna (before 130 BC – early 84 BC) was a four-time consul of the Roman republic. Opposing Sulla's march on Rome in 88 BC, he was elected to the consulship of 87 BC, during which he engaged in an armed conflict – the Bellum Octavianum – with his co-consul, Gnaeus Octavius. Emerging victorious, Cinna initiated with his ally, Gaius Marius, the murders of their enemies. In the aftermath, he dominated the republic for the next three years, serving continuously as consul.

While his domination was not complete – he largely contented himself with securing the consulship for himself and allies – his political rule set a "crucial precedent" for later strongmen in the republic. Through 85 and 84 BC, he prepared for war against Sulla, who was soon to return from the First Mithridatic War. Cinna was killed by his own troops, who mutinied during his attempt to cross the Adriatic at Ancona early in 84 BC.

Quintus Sertorius (c. 126 BC – 73 or 72 BC) was a Roman general and statesman who led a large-scale rebellion against the Roman Senate on the Iberian Peninsula. Defying the regime of Sulla, Sertorius became the independent ruler of Hispania for most of a decade until his assassination.

Sertorius first became prominent during the Cimbrian War fighting under Gaius Marius, and then served Rome in the Social War. After Lucius Cornelius Sulla blocked Sertorius' attempt at the plebeian tribunate c. 88 BC, following Sulla's consulship, Sertorius joined with Cinna and Marius in the civil war of 87 BC. He led in the assault on Rome and restrained the reprisals that followed. During Cinna's repeated consulships he was elected praetor, likely in 85 or 84 BC. He criticised Gnaeus Papirius Carbo and other Marians' leadership of the anti-Sullan forces during the civil war with Sulla and was, late in the war, given command of Hispania.

Quintus Lutatius Catulus (149–87 BC) was a consul of the Roman Republic in 102 BC. His consular colleague was Gaius Marius. During their consulship the Cimbri and Teutones marched south again and threatened the Republic. While Marius marched against the Teutones in Gaul, Catulus had to keep the Cimbri from invading Italy. In this he failed; the Cimbri succeeded in invading the Po Valley. In 101 BC Catulus, as proconsul, continued the war against the Cimbri. Marius, elected consul for the fifth time, joined him and together they campaigned against the Germanic invaders in the Po Valley. At the Battle of Vercellae Marius and Catulus decisively defeated the Cimbri and ended the Germanic invasion. After Vercellae the two feuded, and Catulus consequently committed suicide following Marius's victory in the civil war of 87 BC.