The famous Philip of Macedon succeeded to the Macedonian throne in 359 B. C., at the age of 23. In his youth he had been delivered to the Thebans as one of the hostages given upon the conclusion of a treaty of peace in 368. "His residence at Thebes gave him some tincture of Grecian philosophy and literature; but the most important lesson which he learned at that city was the art of war, with all the improved tactics introduced by Epaminondas. Philip … displayed at the beginning of his reign his extraordinary energy and abilities. After defeating the Illyrians he established a standing army, in which discipline was preserved by the severest punishments. He introduced the far-famed Macedonian phalanx, which was 16 men deep, armed with long projecting spears. Philip's views were first turned towards the eastern frontiers of his dominions, where his interests clashed with those of the Athenians. A few years before the Athenians had made various unavailing attempts to obtain possession of Amphipolis, once the jewel of their empire, but which they had never recovered since its capture by Brasidas in the eighth year of the Peloponnesian war." _W. Smith, Smaller History of Greece, chapter 19._ The importance of Amphipolis to the Athenians arose chiefly from its vicinity to "the vast forests which clothed the mountains that enclose the basin of the Strymon, and afforded an inexhaustible supply of ship-timber." For the same reason that the Athenians desired ardently to regain possession of Amphipolis their enemies were strong in the wish to keep it out of their hands. Moreover, as the Macedonian kingdom became well-knitted in the strong hands of the ambitious Philip, the city of "the Nine Ways" assumed importance to that rising power, and Philip resolved to possess it. It was at this point that his ambitions first came into conflict with Athens. But the Athenians were not aware of his aims until too late. He deceived them completely, in fact, by a bargain to give help in acquiring Amphipolis for them, and to receive help in gaining Pydna for himself. But when his preparations were complete, he suddenly laid siege to Amphipolis and made himself master of the city (B. C. 358), besides taking Pydna as well. At Athens, "Philip was henceforth viewed as an open enemy, and this was the beginning—though without any formal declaration—of a state of hostility between the two powers, which was called, from its origin, the Amphipolitan War." _C. Thirlwall, History of Greece, chapter 42 (volume 5)._ GREECE: B. C. 357-336. Advancement of Philip of Macedonia to supremacy. The Sacred Wars and their consequences. The fatal field of Chæronea. Philip's preparations for the invasion of Asia. His assassination.