Triumvirate, in ancient Rome, ruling board or commission of three men. Triumvirates were common in the Roman republic. The First Triumvirate was the alliance of Julius Caesar, Pompey, and Marcus Licinius Crassus formed in 60 B.C. This was not strictly a triumvirate, since the alliance had no official sanction. The three men were able to control Rome, and the alliance aided Caesar's rise to power by giving him the opportunity to pursue the Gallic Wars. The Second Triumvirate was legally established as the tresviri rei publicae constituendae [triumvirate for reestablishing the public welfare] in 43 B.C. for five years; it was renewed in 37 B.C. The members were Octavian (Augustus), Marc Antony, and Marcus Aemilius Lepidus (d. 13 B.C.). This group was granted enormous power by the senate. Lepidus was deposed in 36 B.C., and Antony was defeated at Actium in 31 B.C., leaving Octavian at the head of the Roman Empire.

In ancient Rome, usually a board of three officials who assisted higher magistrates in judicial functions, oversaw festival banquets, or ran the mint. The First Triumvirate (60 BC) of Pompey, Julius Caesar, and Crassus was an informal group of three strong leaders with no sanctioned powers. The Second Triumvirate (43 BC), consisting of Mark Antony, Lepidus, and Octavian (later Augustus)—formally tresviri rei publicae constituendae (“triumvirate for organizing the state”)—held absolute dictatorial power.

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