Triumvirate
2 of the 7 encyclopedias on this shelf carry an entry for Triumvirate. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
a coalition of three men in office or applied to two great coalitions of the authority; specifically three most powerful individuals in the Roman empire for the time being. The first of these was effected in the year 60 B. C., between Julius Cæsar, Pompey, and Crassus, who pledged themselves to support each other with all their influence. This coalition was broken by the fall of Crassus at Carrhæ in Mesopotamia; soon after which the civil war which ended with the death of Pompey, broke out, and establishment of Julius Cæsar as perpetual dictator. After his murder, 44 B. C., the civil war again broke out; and after the battle of Mutina, 43 B. C., Antony, Octavius, and Lepidus coalesced, thus forming the second triumvirate. They divided the provinces of the empire; Octavius taking the West, Lepidus Italy, and Antony the East. military highroad. The trocha played an
Aiton's Encyclopedia (1910)
in Roman history, an agreement or alliance formed between three men. The First Triumvirate was formed 60 B. C. between Caesar, Pompey, and Crassus. Caesar had command of the field forces in Gaul; Pompey was made commissioner of corn supplies; Crassus had command in the east, where he was killed in 53 B. C. The Triumvirate ended in the civil war of 49 B. C., by which Caesar became supreme. The Second Triumvirate was formed in 43, between Octavius, Mark Antony, and Lepidus. The conspirators, for we may call them that, met on an island near Bologna. Octavius received command of the west, Antony of the east, and Lepidus of Africa. Octavius, known in history as Augustus, used the armies for his own purposes. In 31 B. C. he became supreme. See Caesar ; Pompey ; Crassus; Antony ; Octavius