Titus Livius (Livy) Ab urbe condita 44.35.8

[8] Others advised that Octavius with his fleet should make for Thessalonica and by ravaging the coastal area create a diversion of the king's forces, so that on the appearance of another attack in his rear the king would be pulled about to guard the inner part of his kingdom and be compelled to open a crossing somewhere over the Elpeüs. The consul himself regarded the riverbank as impregnable by nature and by fortification and, besides the fact that artillery had been placed everywhere, he had heard that the enemy employed missile weapons better and with more deadly aim. ¹

[8] For he considered that He resolved to employ those two men as guides; and, sending for the praetor Octavius, explained to him what he intended, ordering him to sail directly with the fleet to Heracleum, and to have in readiness, there, ten days' provisions for one thousand men. He then sent Publius Scipio Nasica, and Quintus Fabius Maximus, his own son, with five thousand chosen men, to Heracleum, as if they were to embark in the fleet, to ravage the coast of the interior parts of Macedonia, as had been proposed in the council. He told them, in private, that there were provisions prepared for them on board, so that they should have no delay.

[8] By thus menacing his rear they would compel the king to divide his forces and march away to protect the interior of his kingdom, thus leaving the passage of the river in some direction open. The consul considered the river bank insurmountable, owing to its steepness and the works which defended it, especially as artillery was in position everywhere, and he had heard that the enemy used their missile weapons more skillfully, and with a surer aim.