The epic poem Bellum Civile by the Roman poet M. Annaeus Lucanus, a contemporary of the emperor Nero (1st century A.D.), deals with the great civil war between Julius Caesar and Pompey in 49-47 B.C. Their conflict is elaborated in powerful verses full of paradoxes, pointed sententiae and vehement pathos. The present commentary is devoted to Book 3, which is dominated by a fascinating catalogue of Pompey's troups, and a highly original account of a naval battle delivered near Massilia.