The only Boeotian troops that did continue to fight — the light infantry attached to the victorious cavalry — worked their way over to the Athenians on the right, where most of them were killed. The collapse of Boeotian morale at the death of Epaminondas and the abrupt cessation of fighting remain something of an enigma, especially since Pelopidas' men at Cynoscephalae fought even more vigorously to preserve the victory after he fell there.
Source: wiktionary