Thebes built its elite fighting unit from 150 pairs of lovers
The Sacred Band of Thebes was 300 hand-picked infantrymen, arranged as 150 couples of an older lover and a younger beloved who swore vows at a hero's shrine. For about four decades it was the sharpest blade in the Theban army, helping break Sparta at Leuctra before Philip II destroyed it at Chaeronea.
The generally accepted founding date is 379 to 378 BC, just after Thebes expelled a Spartan garrison from its citadel, the Cadmea. Plutarch, who came from Chaeronea and wrote the fullest account, credits the commander Gorgidas, who chose men for merit alone, whatever their class. Other ancient writers name Epaminondas as founder instead, and one modern historian argues Gorgidas only reformed an older unit, since Theban forces of 300 picked men appear in accounts of earlier battles. Plutarch traced the word sacred to vows exchanged at the shrine of Iolaus, remembered as a lover of Heracles.
The band lived as a standing garrison on the Cadmea, trained and housed at public expense, practising wrestling and dance. Historian James DeVoto estimates members joined at 20 or 21, receiving armour from their older partners, and served until about 30. Gorgidas first scattered them through the front ranks of ordinary troops. After Pelopidas took over in 375 BC, they fought as one shock unit designed to kill the enemy's best men and leaders.
An early test came in 378 BC, when Spartan king Agesilaus II advanced on a Theban and Athenian line. With the armies about 200 metres apart, the Athenian commander Chabrias ordered his mercenaries to stand at ease, spears upright and shields resting on knees. Gorgidas had the Sacred Band copy him with the same crisp discipline. The display of calm unsettled Agesilaus enough that he halted and withdrew.
The unit also drew in the philosophers. Xenophon's Socrates frowns on Thebes and Elis for posting lovers side by side in battle, and Phaedrus in Plato's Symposium imagines an army of lovers; scholars such as Kenneth Dover have used these passages to argue about which Symposium came first. The earliest surviving mention of the band by name comes from an Athenian speech of 324 BC.
Source: Sacred Band of Thebes