Marius, Caius (mârˈēəs) [key], c.157 B.C.–86 B.C., Roman general. A plebeian, he became tribune (119 B.C.) and praetor (115 B.C.) and was seven times consul. He served under Scipio Africanus Minor at Numantia and under Quintus Metellus against Jugurtha. Later, when he was commander of Roman forces against Jugurtha, he hastened the end of the war by a bold attack against the Numidians. In 102 B.C. he defeated the Teutones at Aix, and the next year he bested the Cimbri at Vercelli. Rivalry with Sulla over the command against Mithradates VI of Pontus turned into civil war; Sulla won, and Marius fled Rome. When Sulla went off to fight, Marius, now allied with the consul Cinna, returned and slaughtered (88 B.C.) his opponents. Marius was a great general, whose military reforms resulted in a professional soldiery with political influence, but he was also capable of great treachery in furthering his own ambitions.
See biography by T. F. Canney (2d. ed. 1970).