Bret Devereaux

The Greek reads, "ὁ λόχος ἦν ἐρασταὶ καὶ ἐρώμενοι τριακόσιοι." "The lochos (unit) were 300 lovers and beloveds" - ἐρασταὶ and ἐρώμενοι are the same terms Plutarch uses and are the unambiguous technical terms for men in a physical homosexual relationship. 9/19

Athenaeus of Naucratis (13.78) also reports this. Once again, the public domain translations you'll find (Yonge: "For in the presence of his favourite, a man would chose to do anything rather than get the character of a coward") are rather less blunt than the Greek. 10/19

The Greek reads something closer to, "A lover, in the presence of his darling boy (παιδικῶν - it's an idiomatic use of παιδικός - adj. meaning 'boyish' but see the LSJ entry, A.III.2 for the substantive use meaning something like 'boyfriend' or 'darling')... 11/19

...would do anything rather than think himself to have been taken as a coward by his darling." To be clear, both 'lover' and 'darling' here are explicitly male, Greek being one of those languages with clear grammatical genders. 12/19

Athenaeus then provides the Sacred Band of Thebes (he thinks it was founded by Epaminondas, not Gorgidas) as an example of this principle in action. 13/19

Now it is true none of these sources are contemporary to the band itself; Plutarch is early second century, Polyaenus is mid/late-second century and Athenaeus is late-second/early-third century. But there's no alternative tradition here. 14/19

So the original tweet is simply wrong in a lazy, unambiguous way. There are interesting debates to be had over other questions, like if Achilles&Patroclus were intended to be lovers in the text of the Iliad, or the details of Greek attitudes towards homosexuality. 15/19

But this isn't one of those. Honestly, given how limited & often contradictory ancient source material is, how difficult archaeological evidence can be, it is a real challenge to manage to be decisively wrong on a point where there is no uncertainty. Mission accomplished? 16/19