His son, Gaius Cassius Longinus, would later help assassinate Gaius Julius Caesar in 44 BC.
As proconsul of Cisalpine Gaul in the next year, 72 BC, during the Third Servile War, Cassius tried to stop Spartacus and his followers near Mutina (modern day Modena) as the slave army was trying to break through to unoccupied Gaul, but suffered defeat and barely managed to get away alive.
Two years later, Cassius appeared as witness of the prosecution in the trial against the corrupt former governor of Sicily, Verres. In 66 BC, Cassius supported the Manilian law that gave command of the war against Mithridates to Pompey; he was joined in this by Cicero, then praetor, whose famous speech in support of the same bill survives.
Varus was a well trained fighter, able to defeat many rebels during Spartacus' attack.