Titus Livius (Livy), The History of Rome, Book 32
Cyrus Evans, Ed.

5. There, whilst others, glad of any interval of rest, consigned both body and mind to repose, [2??] Philip, in proportion as the season of the year had relieved him from the incessant fatigues of marching and fighting, found his care and anxiety increase the more, when he turned his thoughts towards the general issue of the war. [3] He dreaded, not only his enemies, who pressed him hard by land and sea, but also the dispositions, sometimes of his allies, at others of his own subjects, lest the former might be induced, by hopes of friendship with the Romans, to revolt, and the Macedonians themselves be seized with a desire of innovation. [4] Wherefore, he despatched ambassadors to the Achaeans, both to require their oath, (for it had been made an article of their agreement that they should take an oath prescribed by Philip every year,) and at the same time to restore to them Orchomenes, Heraea, and Triphylia. [5] To the Eleans he delivered up Aliphera; which city, they insisted, had never belonged to Triphylia, but ought to be restored to them, having been one of those that were incorporated by the council of the Arcadians for the [p. 1399]funding of Megalopolis. [6] These measures had the effect of strengthening his connexion with the Achaeans. [7] The affections of the Macedonians he conciliated by his treatment of Heraclides: for, finding that his having countenanced this man had been the cause to him of the utmost unpopularity, he charged him with a number of crimes, and threw him into [8??] chains, to the great joy of the people. [9] It was now, if at any time, that he made preparations for the war with especial energy. He exercised both the Macedonian and mercenary troops in arms, and in the beginning of spring sent Athenagoras, with all the foreign auxiliaries and what light-armed troops there were, through Epirus into Chaonia, to seize the pass at Antigonia, which the Greeks called Stena. [10] He followed, in a few days, with the heavy troops: and having viewed every situation in the country, he judged that the most advantageous post for fortifying himself was on the river Aous. [11] This river runs in a narrow vale, between two mountains, one of which the natives call Aeropus, and the other Asnaus, affording a passage of very little breadth along the bank. He ordered Athenagoras, with the light infantry, to take possession of Asnaus, and to fortify it. His own camp he pitched on Aeropus. Those places where the rocks were steep, were defended by guards of a few soldiers only; the less secure he strengthened, some with trenches, some with ramparts, and others with towers. [12] A great number of engines, also, were disposed in proper places, that, by means of weapons thrown from these, they might keep the enemy at a distance. [13] The royal pavilion was pitched on the outside of the rampart, on the most conspicuous eminence, in order, by this show of confidence, to dishearten the foe, and raise the hopes of his own men.