Gnaeus Domitius Ahenobarbus, a member of the noble Ahenobarbus family, accompanied his father at Corfinium and Pharsalus, and, having been pardoned by
Julius Caesar, returned to
Rome in
46 BC.
After Caesar's assassination he attached himself to
Marcus Junius Brutus and
Cassius, and in
43 BC was condemned by the
lex Pedia as having been implicated in the plot.
He obtained considerable naval successes in the Ionian Sea against the
Second Triumvirate, but finally, through the mediation of
Gaius Asinius Pollio, became reconciled to
Mark Antony, who made him governor of
Bithynia.
He took part in Antony's Parthian campaigns, and was
consul in
32 BC. When war broke out between Antony and Octavian, he at first supported Antony, but, disgusted with his intrigue with
Cleopatra VII of Egypt, went over to Octavian shortly before the
battle of Actium (
31 BC). He died soon afterwards (Dio Cassius xlviii.-l; Appian,
Bell. Civ. iv., v.).