1. C.Sosius, was quaestor of M'. Lepidus, consul B. C. 66 He was praetor in B. C. 49, on the breaking out of the civil war, and, like most of the other magistrates of that year, belonged to the Pompeian party. He did not, however, remain with this party long; for instead of going to Brundusium to cross the sea with Pompey, he returned to Rome with Lupus and openly united himself to Caesar (Cic. Att. 8.6, 9.1). After the death of Caesar he followed the fortunes of Antony, whom he accompanied to the East, and by whom he was appointed in B. C. 38 governor of Syria and Cilicia in the place of Ventidius. Like his predecessor in the government, he carried on the military operations in his province with great success. He was commanded by Antony to give vigorous support to Herod against Antigonus, the representative of the Asmonaean line of princes, who was in possession of Jerusalem, and had hitherto successfully resisted the efforts of Herod to subdue him. Sosius obtained possession of the island and town of Aradus off the coast of Phoenicia, towards the end of B. C. 38. In the following year, B. C. 37, he advanced against Jerusalem along with Herod, and after hard fighting became master of the city, and placed Herod upon the throne. (D. C. 49.22; J. AJ 14.15, 16, B. J. 1.17-18; Tac. Hist. 5.9; Plut. Ant. 34.) [HERODES.] In return for these services, Antony obtained for Sosius the honour of a triumph in B. C. 34, and the consulship along with Cn. Domitius Ahenobarbus in B. C. 32. In the atter year the quarrels and misunderstandings between Octavian and Antony broke out into open hostilities. Sosius warmly espoused the cause of his patron, and in an assembly of the senate on the 1st of January ventured to attack Octavian, and uphold the cause of Antony. Octavian was absent from Rome at the time, and on his return to the city Sosius found it necessary to quit Italy and betake himself to Antony. In the following year, B. C. 31, he commanded a squadron of Antony's fleet ; and during the absence of Agrippa, who had the supreme command of the fleet of Octavian, he attacked the squadron of L. Arruntius and put it to flight; but while engaged in the pursuit, he fell in with M. Agrippa, who wrested the victory from him, killed his ally Tarcondimotus, the king of Cilicia, and compelled Sosius himself to seek safety in flight. It is erroneously stated by Dio Cassius (1. 14) that Sosius fell in this engagement. In the decisive battle of Actium, Sosius commanded the left wing. He escaped from the battle and fled to a place of concealment, but was detected and brought to Octavian. The conqueror pardoned him, however, at the intercession of L. Arruntius (Suet. Aug. 17 ; Appian. B. C. 5.73; D. C. 49.41, 1. 2, 14, 51.2, 56.38; Vell. 2.85, 86). There are several coins of this C. Sosius extant. The specimen annexed has on the obverse the head of Antony, and on the reverse an eagle standing on a thunderbolt, with a caduceus before it, and the legend C. SOSIVS Q. (Eckhel, vol. v. p. 314.)