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 a part of, include the rapid construction 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.