[2] During his term as praetor in 63 BC, he played a role in suppressing the Catilinarian conspiracy: he intercepted the communications between Catiline's urban conspirators and the Allobroges on the Mulvian bridge, giving the incriminating letters recovered to Cicero.
[3] After his praetorship he served as governor in Transalpine Gaul, possibly pro praetore,[4] fighting the Allobroges.
[5] He may have remained in Gaul until 59 since his intended successor, the Quintus Caecilius Metellus Celer who was consul in 60, died before taking up the post.
[6] While a plebeian tribune of 59 BC, Publius Vatinius, attempted to disrupt recognition of his successes that year,[7] he retained his imperium and eventually secured in 54 – with the support of then-praetor and former subordinate Servius Sulpicius Galba[8] as well as then-consul Appius Claudius Pulcher – a triumph for his victories in Gaul.
[9] He joined Cicero's staff in Cilicia from 51 – 50, playing an important role in the military side of operations there.