5. C.PopilliusLaenas, P. F. P. N., brother to the two preceding ones, was consul (B. C. 172) in the year after his brother Marcus had so shamefully treated the Ligurians. He supported his brother, and warded off his punishment. He was the first plebeian consul who had a plebeian for a colleague (Fast. Capitol.); and he served afterwards as legate in Greece. (Liv. 43.19, 24.) The haughtiness of his character is most apparent in his behaviour as ambassador to Antiochus, king of Syria, whom the senate wished to abstain from hostilities against Egypt. Antiochus was just marching upon Alexandria when he was met by the three Roman ambassadors. Popillius transmitted to him the letter of the senate, which Antiochus read and promised to take into consideration with his friends. Then Popillius described with his cane a circle in the sand round the king, and ordered him not to stir out of it before he had given a decisive answer. This boldness so frightened Antiochus, that he at once yielded to the demand of Rome. (Liv. 45.12; Polyb. Exc. Legat. 92; V. Max. 6.4; Vell. 1.10; App. Syr. 131.) C. Popillius was consul a second time B. C. 158.
A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890