Titus Livius (Livy), The History of Rome, Book 32
Evan T. Sage, Ph.D. Professor of Latin and Head of the Department of Classics in the University of Pittsburgh, Ed.

5. There the rest devoted to relaxation of mind and body alike whatever little quiet time was allowed them; [2] Philip, however great relief of mind he had obtained after the ceaseless labour of marching and fighting, was so much the more concerned and worried about the final outcome of the war, not only fearing the enemy, who was pressing upon [3] him by land and sea, but distrusting the attitude now of his allies, now even of his subjects, fearing both that the former should revolt, in the hope of an alliance with the Romans, and that the Macedonians themselves should be inspired by a desire for revolution. [4] So he sent ambassadors to Achaea, partly to demand the oath¹ —for they had agreed to renew annually their pledges of loyalty to him —and [5] partly to restore [p. 165]to the Achaeans Orchomenus and Heraea, and also² Triphylia which had been taken from the Eleans, and to the Megalopolites Aliphera, since they argued that this city had never belonged to Triphylia, but should be given back to them, since it was one of the towns that had been turned over to form the city of Megalopolis in accordance with the decree of the Arcadian council. [6] And with the Achaeans indeed he did by these measures strengthen the alliance; [7] but with regard to the disposition of the Macedonians, since he realized that his friendship with Heraclides was particularly a source of unpopularity for him, he heaped accusations upon him and [8] threw him into prison, to the great joy of the people. [9] Philip at this time made preparation with great energy, if he had ever done so before, on any occasion, and drilled both his Macedonians and his mercenary troops, and in the beginning of spring sent all his foreign auxiliaries and what light-armed troops he had, under Athenagoras, to Chaonia by way of Epirus, to hold the passes leading to Antigonea —the Greeks call them The Narrows. [10] He himself followed a few days later with the heavier troops, and when he had reconnoitred the whole region, he determined upon a site near the river Aous as the most suitable place for a fortified base of operations. [11] This river, flowing through a defile between ranges, one called by the natives Meropus, the other Asnaus, leaves a narrow road along the bank. He ordered Athenagoras and the light troops to hold and fortify Asnaus; he himself pitched camp on Meropus. [12] Where the cliffs were steep, a guard of a few armed men held them; where they were less defensible, they were protected, some by ditches, [p. 167]some by ramparts, some by towers. Numerous³ pieces of artillery were also posted in suitable places, to keep the enemy at a distance with their missiles. [13] The royal headquarters he established in plain sight on a hill in front of the rampart, to inspire terror in the enemy and in his own men the hope that springs from confidence.