At what precise moment, during the lifetime of his father, Alexander first took part in active service, we do not know. It is said that once, when quite a youth, he received some Persian envoys during the absence of his father; and that he surprised them by the maturity of his demeanor, as well as by the political bearing and pertinence of his questions.[3] Though only sixteen years of age, in 340 B. C., he was left at home as regent while Philip was engaged in the sieges of Byzantium and Perinthus. He put down a revolt of the neighboring Thracian tribe called Mædi, took one of their towns, and founded it anew under the title of Alexandria; the earliest town which bore that name, afterwards applied to so many other towns planted by him. In the march of Philip into Greece (338 B. C.), Alexander took part, commanded one of the wings at the battle of Chæroneia, and is said to have first gained the advantage on his side over the Theban sacred band.[4] [3] Plutarch, Alex. 5. [4] Plutarch, Alex. 9. Justin says that Alexander was the companion of his father during part of the war in Thrace (ix. 1). Yet notwithstanding such marks of confidence and coöperation, other incidents occurred producing bitter animosity between the father and the son. By his wife Olympias, Philip had as offspring Alexander and Kleopatra: by a Thessalian mistress named Philinna, he had a son named Aridæus (afterwards called Philip Aridæus:) he had also daughters named Kynna (or Kynanê) and Thessalonikê. Olympias, a woman of sanguinary and implacable disposition, had rendered herself so odious to him, that he repudiated her, and married a new wife named Kleopatra. I have recounted in the preceding volume[5] the indignation felt by Alexander at this proceeding, and the violent altercation which occurred during the conviviality of the marriage banquet; where Philip actually snatched his sword, threatened his son’s life, and was only prevented from executing the threat by falling down through intoxication. After this quarrel, Alexander retired from Macedonia, conducting his mother to her brother Alexander king of Epirus. A son was born to Philip by Kleopatra. Her brother or uncle Attalus acquired high favor. Her kinsmen and partisans generally were also promoted, while Ptolemy, Nearchus, and other persons attached to Alexander, were banished.[6] [5] Vol. XI. Ch. xc. p. 513. [6] Plutarch, Alex. 10. Arrian, iii. 6, 8.