Arrian · 85–175
Death of Philip and Accession of Alexander.—His Wars with the Thracians.
It is said that Philip died 14 when Pythodemus was archon at Athens, 15 and that his son Alexander, 16 being then 9 about twenty years of age, marched into Peloponnesus 17 as soon as he had secured the regal power. There he assembled all the Greeks who were within the limits of Peloponnesus, 18 and asked from them the supreme command of the expedition against the Persians, an office which they had already conferred upon Philip. He received the honour which he asked from all except the Lacedaemonians, 19 who replied that it was an hereditary custom of theirs, not to follow others but to lead them. The Athenians also attempted to bring about some political change; but they were so alarmed at the very approach of Alexander, that they conceded to him even more ample public honours than those which had been bestowed upon Philip. 20 He then returned into Macedonia and busied himself in preparing for the expedition into Asia.
However, at the approach of spring ( B.C. 335), he marched towards Thrace, into the lands of the Triballians and Illyrians, 21 because he ascertained that these nations were meditating a change of policy; and at the same time, as they were lying on his frontier, he thought it inexpedient, when he was about to start on a campaign so far away from his own land, to leave them behind him 10 without being entirely subjugated. Setting out then from Amphipolis, he invaded the land of the people who were called independent Thracians, 22 keeping the city of Philippi and mount Orbelus on the left. Crossing the river Nessus, 23 they say he arrived at mount Haemus 24 on the tenth day. Here, along the defiles up the ascent to the mountain, he was met by many of the traders equipped with arms, as well as by the independent Thracians, who had made preparations to check the further advance of his expedition by seizing the summit of the Haemus, along which was the route for the passage of his army. They had collected their waggons, and placed them in front of them, not only using them as a rampart from which they might defend themselves, in case they should be forced back, but also intending to let them loose upon the phalanx of the Macedonians, where the mountain was most precipitous, if they tried to ascend. They had come to the conclusion 25 that the denser the phalanx was with which the waggons rushing down came into collision, the more easily would they scatter it by the violence of their fall upon it.