Gaius Marcius Censorinus is first mentioned in historical chronicles after the return of Lucius Cornelius Sulla from Asia.
[1] With the outbreak of the First Civil War of the Roman Republic, Marcius Censorius joined the ranks of Gaius Marius and Lucius Cornelius Cinna in their efforts to combat Sulla.
When Gnaeus Octavius (Consul in 87 BC) was added to the prescribed lists, it was Marcius Censorinus who executed him and took his head to Cinna.
In mid 82 BC, Marcius Censorius was sent to fight Pompey Magnus and was defeated at Sena Galica with Papirius Carbo.
After this decisive defeat, Censorinus and the Populares army retreated to the Sebellian region where the Samnites had enlisted a thousand soldiers to free Marius the Younger from his siege.
He was beheaded at Sulla's orders and his head was sent to Preneste to lower the morale of the troops under the command of Gaius Marius the Younger.