At this time the Achaeans were carrying on war with Machanidas the tyrant of Sparta, who, relying upon his large and strong forces, was scheming to get control of the whole Peloponnesus. Accordingly, when word came that the tyrant had invaded the territory of Mantineia, Philopoemen quickly led his army out against him. They drew up in battle array near the city, both parties having many mercenaries and almost all their citizen soldiery.
When battle was joined, Machanidas with his mercenaries routed the javelineers and Tarantines who had been stationed in front of the Achaean line, and then, instead of advancing directly against the main body of the enemy and breaking up their close array, he dashed off in pursuit of the fugitives, and so passed by the phalanx of the Achaeans, which remained drawn up in position.
Then Philopoemen, although so great a disaster had occurred at the outset and his cause was thought to be utterly lost and ruined, professed to ignore and make light of it, and seeing what a great mistake the enemy had made by going off in pursuit, thus breaking away from his phalanx and leaving a vacant space there, did not oppose or resist their chase after the fugitives, but let them pass him by and make a great gap.
Then he led straight against the Lacedaemonian heavy-armed, seeing that their phalanx had been left exposed, and fell upon them in a flank attack, while their commander was away and they were not expecting to fight; for they thought they were victorious and getting the upper hand altogether, since they saw Machanidas pursuing.
After Philopoemen had routed these with great slaughter (more than four thousand of them are said to have fallen), he set out against Machanidas, who was returning with his mercenaries from the pursuit. But a broad and deep ditch stretched between them, along which the two leaders rode opposite each other, one wishing to get across and escape, the other to prevent this.
The spectacle was not that of two commanders fighting, but that of a powerful hunter attacking a wild beast that has been forced to turn at bay, and Philopoemen was the hunter. And now the tyrant's horse, which was vigorous and high-spirited and felt the bloody spurs in his sides, essayed to make the leap across, and striking against the edge of the ditch with his breast, was struggling with his fore-feet to extricate himself.
At this point Simmias and Polyaenus, who were always at Philopoemen's side when he was fighting and protected him with their shields, rode up both at the same time and levelled their spears at the horse. But Philopoemen was before them in attacking Machanidas, and seeing that the tyrant's horse was lifting its head up in front of its rider's body, he gave his own horse a little swerve to one side, and then, clasping his spear firmly in the middle, pushed it home with all his weight and overturned his enemy.
This is the attitude in which he is represented by a bronze statue set up at Delphi by the Achaeans, who admired especially both his deed of prowess and his generalship on that day.