Sosthĕnes in Harpers Dictionary of Classical Antiquities (1898)
（Σωσθένης). A Macedonian soldier who defeated the Gauls at the time of their invasion of Greece in B.C. 280 (Just. xxiv. 5, 6). See Gallia.
Sosthenes of Macedon in Wikipedia
Sosthenes (Greek Σωσθένης d. 277 BC) was a Macedonian and general and may have been a king of the Antipatrid dynasty. During the reign of Lysimachus he was his governor in Asia Minor. Sosthenes was elected King by the Macedonian army, but he may or not have reigned as king. Appointed as Strategos he may have declined the title of king as he had no royal connections. During his reign he faced invading Gauls, Antigonus Gonatas and other rivals. He defeated Bolgius, one of the earliest invading Gallic chiefs but was soon faced with the invasion of Brennus in the summer of 279 BC. Antigonus Gonatas tried to invade Macedonia from Asia in 278 but was beaten by Sosthenes.