Titus Livius (Livy), The History of Rome, Book 37
Evan T. Sage, PhD professor of latin and head of the department of classics in the University of Pittsburgh, Ed.

20. About this time there arrived at Elaea from Achaea one thousand infantry and one hundred cavalry, all under the command of Diophanes,¹ and when they debarked guides, sent by Attalus to meet them, escorted them by night to Pergamum. [2] They were all veterans and skilled in war, and their leader too was a pupil of Philopoemen,² at that time the foremost general of all the Greeks. They took two days for the double purpose of resting men and horses and reconnoitring the enemy's dispositions and learning at what times and places they advanced and retired. [3] The king's troops would come up to about the base of the hill on which the town stood; thus the rear area was open for foraging. When no one came out of the city, not even to throw a javelin from a distance against the outposts, [4??] after the people had once, under the impulse of fear, shut themselves up within the walls, a feeling of contempt for them and hence carelessness arose among the forces of [p. 349]the king. [5] A large part of them had no saddles or³ bridles for their horses; a few being left with the arms and at their posts, the rest were scattered and dispersed here and there over the whole plain, some engaged in youthful play and pastime, some picnicking in shady spots, some even lying asleep. [6] Diophanes, watching this from the high-lying city of Pergamum, ordered his men to take their arms and be ready at the gates; he himself went to Attalus and told him that it was his purpose to make an attempt on an outpost of the enemy. [7] When Attalus allowed it reluctantly, seeing that there were one hundred cavalry against six hundred, one thousand infantry against four thousand, Diophanes marched out of the gate and took his place not far from the outpost of the enemy, watching his chance. [8] Both the people in Pergamum believed this to be folly rather than fearlessness, and the enemy, having watched them for a while and seen no signs of activity, themselves made no change in their customary carelessness, especially since they were scornful of their small numbers. [9] Diophanes kept his men quiet for a while, as if they had been led out merely to watch a show; [10] when he saw that the enemy had broken ranks, ordering the infantry to follow as fast as they could, he himself, at the head of the cavalry with his own troop, the horses being given the loosest possible rein, and a shout raised at the same moment by every footman and trooper, attacked the outpost of the enemy without warning. [11] Not the men alone but even the horses were terrified, and when they broke their halters they caused consternation and confusion among their own men. [12] A few horses [p. 351]stood fearlessly; even these they could not easily⁴ saddle or bridle or mount, the Achaeans causing far more terror than was warranted by the number of troopers. But the infantry, in formation and ready, attacked men who were scattered around in disorder and nigh half asleep. [13] There was slaughter and flight everywhere through the plains. [14] Diophanes pursued the fugitives as far as it was safe, having won great glory for the Achaean people —for both men and women were watching from the walls of Pergamum —and returned to the garrisoning of the city.