Passage 8.50.2
Μαχανίδου δὲ ἐν Λακεδαίμονι ἀναφύντος τυράννου καὶ αὖθις πολέμου τοῖς Ἀχαιοῖς πρὸς Λακεδαιμονίους καὶ Μαχανίδαν συνεστηκότος, ἡγεῖτο μὲν τοῦ Ἀχαϊκοῦ Φιλοποίμην· γινομένης δὲ πρὸς Μαντινείᾳ μάχης Λακεδαιμονίων μὲν οἱ ψιλοὶ τοὺς ἀσκεύους τῶν Ἀχαιῶν νικῶσι καὶ φεύγουσιν αὐτοῖς ἐπέκειτο ὁ Μαχανίδας, τῇ δὲ φάλαγγι ὁ Φιλοποίμην τῶν πεζῶν τρέπεται τῶν Λακεδαιμονίων τοὺς ὁπλίτας καὶ ἀναχωροῦντι ἀπὸ τῆς διώξεως Μαχανίδᾳ συντυχὼν ἀποκτίννυσιν αὐτόν. Λακεδαιμονίοις δὲ ἠτυχηκόσι τῇ μάχῃ περιεγεγόνει μείζων ἢ κατὰ τὸ πταῖσμα εὐτυχία, γεγονόσιν ἐλευθέροις ἀπὸ τοῦ τυράννου.
When Machanidas rose up as tyrant in Sparta, war once more broke out between the Achaeans and the Spartans led by Machanidas. Philopoemen commanded the Achaean forces. A battle took place near Mantineia, in which the Spartan skirmishers defeated the lightly armed Achaeans, and Machanidas himself pursued them in their flight. However, Philopoemen, commanding the phalanx of infantry, routed the Spartan hoplites. As Machanidas was returning from the pursuit, Philopoemen encountered and slew him. For the Spartans, though defeated in battle, their fortune afterward proved greater than their disaster, since by his death they were freed from the tyrant.