The Gauls pulled the wheels up and were dragging the waggons down into the river; but the young Acrotatus saw the danger, and running through the city with three hundred men got round behind Ptolemy without being seen by him, owing to some depressions in the ground, and at last fell upon his rear ranks and forced them to turn about and fight with him. And now the Barbarians crowded one another into the trench and fell among the waggons, and finally, after great slaughter, were successfully driven back.
Edition :
Plutarch Lives IX: Demetrius and Antony, Pyrrhus and Caius Marius, Ed. Jeffrey Henderson, trans. Bernadotte Perrin (The Loeb Classical Library 101), Harvard University Press: Cambridge/MA - London 1968 (first ed. 1920).
Remark :
victim: Details about the victims are taken from 28.1. date: The date is taken from the New Pauly.
http://referenceworks.brillonline.com/entries/brill-s-new-pauly/pyrrhus-e1015710