However, the death of Epaminondas and his intended successors would cost Thebes the military leadership and initiative to maintain Theban supremacy in the region.

Epaminondas' death coupled with the impact on the Spartans of yet another defeat weakened both alliances, and paved the way for Macedonian conquest led by Philip II of Macedon.

Greek General and Statesman Epaminondas (in some sources spelt Epameinondas) headed a revolt against the garrison of Spartan troops in Boeotian territory in 378 B.C.

The battle of Leuctra "led, undeniably, to a wholly different world, in which the Spartans were badly weakened and Thebans wildly emboldened.

[8] The historian Diodorus Siculus made claim that after the Battle of Leuctra, Epaminondas "became the foremost man, not only of Thebes, but of all who lived in his time".

[8] Due to the high regard from his subjects and recent military victory, Epaminondas sought to continue to expand and establish Theban supremacy.

At the behest of the Arcadian League in 370 B.C., Epaminondas led a winter campaign in Laconia, plundering the countryside while King Agesilaus II could only watch in Sparta.

[9] Epaminondas ended this campaign by repopulating Messene, the capital of Messenia, fortifying it with the finest stone walls in all of Greece, causing Sparta to be surrounded with enemies on all sides.

[12] In years prior to the Battle of Mantinea, the Spartans had joined with the Eleans (a minor Peloponnesian people with a territorial grudge against the Arcadians) in an effort to undermine the League.

[21] [22][23] Due to the consecutive setbacks the Thebans faced so far in this campaign, Epaminondas is said to have believed that he must regain his honor through winning a decisive battle.

[22] Xenophon wrote that Epaminondas believed that, since he had so far been unsuccessful in this campaign, "if he were victorious, he would make up for all these things, while if he were slain, he deemed that such an end would be honourable for one who was striving to leave to his fatherland dominion over Peloponnesus.

[citation needed] However, as the Mantineans fled, the Spartans made a last-ditch effort to kill Epaminondas before fleeing by throwing their javelins at him, some of which struck his body.

[36] Epaminondas was mortally wounded when facing the Spartan phalanx by a man variously identified as Anticrates, Machaerion, or Gryllus, son of Xenophon.

[39] According to Polyaenus, after the battle, the Mantineians wanted to send heralds to the Thebans in order to make an agreement about carrying off the dead, but Cineas persuaded them against such an action.

This was because it would take years of training, experience, and resources to produce the seasoned veterans lost in the battle, thus the remnants of the military were left in the hands of the less experienced.

[42] The ultimate result of the battle was to pave the way for the Macedonian rise as the leading force who subjugated the rest of Greece by exploiting the weakness of both the Thebans and the Spartans.