a Roman knight, and probably quaestor in B. C. 59 (Cic. Att. 2.9), espoused Pompey's party in the civil war, and after the loss of the battle of Pharsalia (48) fled to Tyre. Here he remained concealed for some time ; but being joined by several of his party, he endeavoured to gain over some of the soldiers of Sex. Julius Caesar, who was at that time governor of Syria. In this attempt he was successful; but his designs were discovered by Sextus, who, however, forgave him on his alleging that he wanted to collect troops in order to assist Mithridates of Pergamus. Soon afterwards, however, Bassus spread a report that Caesar had been defeated and killed in Africa, and that he himself had been appointed governor of Syria. He forthwith seized upon Tyre, and marched against Sextus; but being defeated by the latter, he corrupted the soldiers of his opponent, who was accordingly put to death by his own troops.

On the death of Sextus, his whole army went over to Bassus, with the exception of some troops which were wintering in Apameia and which fled to Cilicia. Bassus followed them, but was unable to gain them over to his side. On his return he took the title of praetor, B. C. 46, and settled down in the strongly fortified town of Apameia, where he maintained himself for three years. He was first besieged by C. Antistius Vetus, who was, however, compelled to retire with loss, as the Arabian Alchaudonius and the Parthians came to the assistance of Bassus. It was one of the charges brought against Cicero's client, Deitoraus, that he had intended to send forces to Bassus. After the retreat of Antistius, Statius Murcus was sent against Bassus with three legions, but he too received a repulse, and was obliged to call to his assistance Marcius Crispus, the governor of Bithynia, who brought three legions more. With these six legions Murcus and Crispus kept Bassus besieged in Apameia till the arrival of Cassius in Syria in the year after Caesar's death, B. C. 43. The troops of Bassus, as well as those of Murcus and Crispus, immediately went over to Cassius, and Bassus, who was unwilling to join Cassius, was dismissed uninjured. (D. C. 47.26_28; Appian, App. BC 3.77, 78, 4.58, 59; Cic. pro Deiot. 8, 9, ad Att. 14.9, 15.13, ad Fam. 11.1, Philip. 11.13, ad Fam. 12.11, 12; Liv. Epit. 114, 121; Vell. 2.69; Strab. xvi. p.752; J. AJ 14.11, B. J. 1.10.10.)

Appian gives (l.c.) a different account of the origin of the revolt in Syria under Bassus. According to Appian's statement, Bassus was appointed by Caesar commander of the legion under the governor Sex. Julius. But as Sextus gave himself up to pleasure and carried the legion about with him everywhere, Bassus represented to him the impropriety of his conduct, but his reproofs were received with contempt; and shortly afterwards Sextus ordered him to be dragged into his presence, because he did not immediately come when he was ordered. Hereupon the soldiers rose against Sextus, who was killed in the tumult. Fearing the anger of Caesar, the soldiers resolved to rebel, and compelled Bassus to join them.