The Battle of Leuctra 371 BC.
"6.4  After this the Athenians, on their side, proceeded to withdraw their garrisons from the cities and to send after Iphicrates and his ships, and they compelled him to give back everything which he had captured after the time when the oaths were taken at Lacedaemon.  But the Lacedaemonians, on the other hand, while they withdrew both their governors and their garrisons from all the other cities, did not follow this course in the case of Cleombrotus, who was at the head of the army in Phocis and now asked the authorities at home what he should do. Prothous did indeed say that it seemed to him they ought first to disband the army in accordance with their oaths and send round word to the various cities to make contributions, as large as each city chose to make, to the temple of Apollo, and afterwards, in case anyone tried to prevent the cities from being independent, to call together again at that time all who wished to support the cause of independence and lead them against those who opposed it; for he thought, he continued, that in this way the gods would be most favourably inclined toward them and the cities would be least annoyed.  The Lacedaemonian assembly, however, upon hearing these words, came to the conclusion that he was talking nonsense; for at this moment, as it seems, Fate was leading them on; and they sent orders to Cleombrotus not to disband his army, but to lead it at once against the Thebans if they did not leave the cities independent. When, therefore, he learned that, so far from leaving the cities independent, the Thebans were not even disbanding their army, in order that they might marshal themselves against him, under these circumstances he undertook to lead his troops into Boeotia.
Now Cleombrotus did not enter Boeotia from Phocis at the point where the Thebans expected him to enter and where they were keeping guard at a narrow pass; but proceeding by way of Thisbae along a mountainous and unexpected route, he arrived at Creusis, captured its wall, and took twelve triremes belonging to the Thebans.  After accomplishing this exploit and marching up from the sea-coast, he encamped at Leuctra, in the territory of Thespiae. And the Thebans encamped on the opposite hill not very far away, with no allies except the Boeotians. Then his friends went to Cleombrotus and said:  “Cleombrotus, if you let the Thebans escape without a battle, you will be in danger of suffering the uttermost penalty at the hands of your state. For they will remember against you not only the time when you reached Cynoscephalae and laid waste no part of the country of the Thebans, but also the time when, on your later expedition, you were beaten back from effecting your entrance, although Agesilaus always made his entrance by way of Cithaeron. Therefore if you really have a care for yourself or a desire to see your fatherland again, you must lead against these men.” Such were the words of his friends; but his opponents said: “Now is the time when the man will make it clear whether he is in truth partial to the Thebans, as rumour has it.”
 Cleombrotus, then, as he heard these things was spurred on to join battle. The leaders of the Thebans, on the other hand, calculated that if they did not fight, the cities round about would revolt from them and they would themselves be besieged; further, that if the people of Thebes were thus cut off from provisions, the city itself would be in danger of turning against them. And since many of them had been in exile before, they estimated that it was better to die fighting than to be exiled again.  Besides this, they were also somewhat encouraged by the oracle which was reported -- that the Lacedaemonians were destined to be defeated at the spot where stood the monument of the virgins, who are said to have killed themselves because they had been violated by certain Lacedaemonians. The Thebans accordingly decorated this monument before the battle. Furthermore, reports were brought to them from the city that all the temples were opening of themselves, and that the priestesses said that the gods revealed victory. And the messengers reported that from the Heracleium the arms also had disappeared, indicating that Heracles had gone forth to the battle. Some, to be sure, say that all these things were but devices of the leaders.  But in the battle, at any rate, everything turned out adversely for the Lacedaemonians, while for the other side everything went prosperously, even to the gifts of fortune. For it was after the morning meal that Cleombrotus held his last council over the battle, and drinking a little, as they did, at the middle of the day, it was said that the wine helped somewhat to excite them.  Again, when both sides were arming themselves and it was already evident that there would be a battle, in the first place, after those who had provided the market and some baggage-carriers and such as did not wish to fight had set out to withdraw from the Boeotian army, the Lacedaemonian mercenaries under Hieron, the peltasts of the Phocians, and, among the horsemen, the Heracleots and Phliasians made a circuit and fell upon these people as they were departing, and not only turned them about but chased them back to the camp of the Boeotians. Thereby they made the Boeotian army much larger and more densely massed than it had been before.  In the second place, since the space between the armies was a plain, the Lacedaemonians posted their horsemen in front of their phalanx, and the Thebans in like manner posted theirs over against them. Now the cavalry of the Thebans was in good training as a result of the war with the Orchomenians and the war with the Thespians, while the cavalry of the Lacedaemonians was exceedingly poor at that time.  For the richest men kept the horses, and it was only when the ban was called out that the appointed trooper presented himself; then he would get his horse and such arms as were given him, and take the field on the moment's notice. As for the men, on the other hand, it was those who were least strong of body and least ambitious who were mounted on the horses.  Such, then, was the cavalry on either side. Coming now to the infantry, it was said that the Lacedaemonians led each half-company three files abreast, and that this resulted in the phalanx being not more than twelve men deep. The Thebans, however, were massed not less than fifty shields deep, calculating that if they conquered that part of the army which was around the king, all the rest of it would be easy to overcome.
 Now when Cleombrotus began to lead his army against the enemy, in the first place, before the troops under him so much as perceived that he was advancing, the horsemen had already joined battle and those of the Lacedaemonians had speedily been worsted; then in their flight they had fallen foul of their own hoplites, and, besides, the companies of the Thebans were now charging upon them. Nevertheless, the fact that Cleombrotus and his men were at first victorious in the battle may be known from this clear indication: they would not have been able to take him up and carry him off still living, had not those who were fighting in front of him been holding the advantage at that time.  But when Deinon, the polemarch, Sphodrias, one of the king's tent-companions, and Cleonymus, the son of Sphodrias, had been killed, then the royal bodyguard, the so-called aides of the polemarch, and the others fell back under the pressure of the Theban mass, while those who were on the left wing of the Lacedaemonians, when they saw that the right wing was being pushed back, gave way. Yet despite the fact that many had fallen and that they were defeated, after they had crossed the trench which chanced to be in front of their camp they grounded their arms at the spot from which they had set forth. The camp, to be sure, was not on ground which was altogether level, but rather on the slope of a hill. After the disaster some of the Lacedaemonians, thinking it unendurable, said that they ought to prevent the enemy from setting up their trophy and to try to recover the bodies of the dead, not by means of a truce, but by fighting.  The polemarchs, however, seeing that of the whole number of the Lacedaemonians almost a thousand had been killed; seeing, further, that among the Spartiatae themselves, of whom there were some seven hundred there, about four hundred had fallen; and perceiving that the allies were one and all without heart for fighting, while some of them were not even displeased at what had taken place, gathered together the most important personages and deliberated about what they should do. And as all thought it best to recover the bodies of the dead by a truce, they finally sent a herald to ask for a truce. After this, then, the Thebans set up a trophy and gave back the bodies under a truce.
 After these things had happened, the messenger who was sent to carry the news of the calamity to Lacedaemon arrived there on the last day of the festival of the Gymnopaediae, when the chorus of men was in the theatre. And when the ephors heard of the disaster, they were indeed distressed, as, I conceive, was inevitable; yet they did not withdraw the chorus, but suffered it to finish its performance. Further, although they duly gave the names of the dead to their several kinsmen, they gave orders to the women not to make any outcry, but to bear the calamity in silence. And on the following day one could see those whose relatives had been killed going about in public with bright and cheerful faces, while of those whose relatives had been reported as living you would have seen but few, and these few walking about gloomy and downcast."( Xen. Hellenica 6.4.3-16):
Xenophon does not mention the numbers on each side, Plutarch says there were 10,000 infantry plus 1,000 cavalry on the Spartan side and 7,00 infantry and 700 cavalry on the Theban side. The order of battle then on both sides was something along these lines, : of Boeotian hoplites there were 7,000 including 4,000 Thebans plus the 300 Sacred Band. Of cavalry the Boeotian League probably provided 700. The Spartans brought 4 mora on a call-up of 35 years making 2,240 (no perioeci being present outside of the Peloponnese except volunteers) plus 300 of the Kings bodyguard (Hippeis). The allies provided 7,000 hoplites from Corinth, Arcadia, Elis and Achaea plus some Phocian peltasts. Of cavalry there would have been 400 Lacedaemonians plus about 600 Arcadian.
Note: Xenophon says that there were only 700 Spartaites at Leuctra, if this total includes the Hippeis then there would have been only 100 Spartaites per Mora. Here I believe Xenophon is only talking about the composition ofthe 4 Mora, he is well aware that the Hippeis are full Spartaites and is not at pains to make this distinction clear to his readers. Even so we have still to account for 370 to 380 others in each Mora. Since they are not Spartaites and as I have stated ealier they were not the regular Perioici, nor were they Neodamodeis as some modern scholars believe, then who were they?. They must be the Hypomoneis (the disenfranchised Spartaites} and probably some volunteer "gentlemen" Perioici and Xenoi.
Epaminondas' two tactical innovations was to oppose his best troops against his opponents best and refuse his weaker wing, combined with the depth of his phalanx this was to prove decisive.
Before the battle, Epaminondas proclaimed that whoever wanted to avoid the fight, could leave the field at that moment. The Thespians tried to leave their post (the right back lines) but the Spartan left flank under Heiron thought that they were trying to manoeuvre so they attacked with their allied cavalry with the support of the Phocian peltasts.
At the beginning, King Cleombrotus ordered the right command of his army (the four Lacedaemonian 'Mora'), to make a manoeuvres to their right in order to overlap the Theban left.. However, the Theban cavalry attacked first and defeated the Spartan cavalry which retreated through the Lacedaemonians infantry causing disorder in their lines.
Why were the cavalry placed in front of the phalanx instead of the usual place on the wing? Possibly Cleombrotus when he saw the depth of the Theban phalanx attempted two things at the same time. firstly to extend his line and secondly to increase the depth of his phalanx and the cavalry were placed to screen this manoeuvre although Plutarch says the Spartan intention was to envelop Epaminondas.
Before the Spartans recovered from the first stroke, the Theban cavalry withdrew to their left and right leaving the field free for the advancing Theban phalanx which, with 50 men deep attacked against the 12 men deep Spartan phalanx.
The Spartans tried to complete their manoeuvres, but Pelopidas with the Theban Sacred Band moved to their left and then forward to cover the Theban left flank catching the Spartans before they could complete their flanking move or reform their line. The Theban attack thus caught the Spartans in confusion..
The Theban phalanx directed the attack to the centre and right where the Kings bodyguard 'Hippies' were located. A murderous conflict ensued. King Cleombrotus was wounded and many Spartans near him including the polemarch Deinon died before him to avoid the capture of his body by the enemy. For a little while the Spartan line held but the death of the King and officers near him added to the confusion and no phalanx 12 deep could prevail against one 50 deep so then the Spartan line at last gave way but in a disciplined way.
When the Peloponnesian and the rest of the Sparta's reluctant allies saw their right flank retreating they also began to retreat to their camp. The Spartans deployed again with discipline behind the ditch of their camp. Their leaders (Cleombrotus was already dead) decided that there was no reason to carry on the fight and asked for a truce with a 'Keryx' (herald). So, the Thebans in accordance with the Greek custom raised a 'Tropaion' and gave the dead men to their opponents. Jason of Pherae is supposed to have persuaded the victorious Thebans to accept the truce.
Of the losses 1,000 of the Lacedaemonians were killed of whom 400 were Spartiates, presumably these were mostly were the 300 of the Kings bodyguard who took the full brunt of the Theban charge. The allies of the Spartans had few casualties as they played little part in the battle. The losses on the Theban side were 300 which included 47 of the Sacred Band.
Result of Battle