He served as praefectus fabrum (prefect of engineers) under Caesar in Gaul; a poem by Catullus also refers to his service in Britain as well as in Pontus and Hispania, suggesting he also served during the civil war. Among the engineering feats achieved by Caesar's army during this time, which Mamurra may have been in charge of, include the throwing of a bridge over the Rhine in 55 BC, the designing and building of a new kind of ship for the second expedition to Britain in 54 BC, and the double circumvallation of Alesia in 52 BC.
Mamurra's military service, and his patronage by Caesar, made him extremely rich. According to Cornelius Nepos he was the first Roman to clad his entire house, on the Caelian Hill, in marble, and the first to use solid marble columns. Catullus attacked his profligacy, womanising and scandalous lifestyle, nicknaming him "mentula" (a vulgar word for the penis) and accusing him of having a homosexual relationship with Caesar. This was regarded as a "lasting stain" on Caesar's character, but Catullus later apologised, and was immediately invited to dinner by Caesar. Catullus also refers in unflattering terms to Ameana, the mistress of "the bankrupt of Formiae", usually taken to mean Mamurra.
A letter of Cicero of 45 BC refers to Caesar giving no visible reaction when he heard news of Mamurra, which has been interpreted by some as referring to his death, although the reference is too ambiguous to be certain.
- Pliny the Elder, Natural History 36.7
- Horace, Satires 1.5
- Catullus, Carmina 29
- Julius Caesar, Commentarii de Bello Gallico 4.17-19
- Caesar, Commentarii de Bello Gallico 5.1
- Caesar, Commentarii de Bello Gallico 7.68-74
- Cicero, Letters to Atticus 7.7
- Catullus, Carmina 57
- Suetonius, Julius 73
- Catullus, Carmina 41, 43
- Cicero, Letters to Atticus 13.52