Titus Livius (Livy), The History of Rome, Book 36
Cyrus Evans, Ed.

30. Manius Acilius having sold, or given to the soldiers, the booty found near Heraclea, and having learned that the counsels adopted at Hypata were not of a pacific nature, but that the Aetolians had hastily assembled at Naupactum, with intention to make [2??] a stand there against the whole brunt of the war, sent forward Appius Claudius, with four thousand men, to seize the heights of the mountains, where the passes were difficult; [3] and he himself, ascending Mount Œta, offered sacrifices to Hercules, in the spot called Pyra,¹ because there the mortal part of the demi-god was burned. He then set out with the main body of the army, and marched all the rest of the way with tolerable ease and expedition. [4] But when they came to Corax, a very high mountain between Callipolis and Naupactum, great numbers of the beasts of burden, together with their loads, tumbled down the precipices, and many of the men were hurt. [5] This clearly showed with how negligent an enemy they had to do, who had not secured so difficult a pass by a guard, and so blocked up the passage; for, even as [p. 1640]the case was, the army suffered considerably. [6] Hence he marched down to Naupactum; and having erected a fort against the citadel, he invested the other parts of the city, dividing his forces according to the situation of the walls. Nor was the siege likely to prove less difficult and laborious than that of Heraclea.