A thread about perceived homoeroticism in popular entertainment and not a single mention of 300? How does that even happen?
Though in the real life Spartan army homosexual sex with fellow soldiers was mandatory, so the homoeroticism probably isn't merely perceived it's probably intentional on the part of the film makers.
One of the funniest historical inaccuracies in 300 is the Spartans mocking the Athenians by basically calling them gay. Maybe that would work with the young men in the audience who can laugh along, but in reality same-sex relationships were extraordinarily common in Ancient Greece and the Spartans specifically viewed it as an important part of the military's social structure. Unlike some groups, however, the Spartans weren't dumb enough to try and structure their units around homosexual companionship among soldiers.
"Dumb enough"?
Following their defeat of Athens, Sparta was defeated by Thebes largely thanks to their legendary Sacred Band, leading to Thebes dominating much of Greece until the Macedonian conquest.
The Sacred Band was only 300 soldiers out of 8500 in the total army. The Thebans won the battle not because the Sacred Band was a bunch of superheroes, but because the Thebans used oblique order (focusing the majority of the push on a single flank of a battle) that was highly unusual at the time (being the first recorded instance of that tactic in history) and generally outmaneuvered the Spartans. The Sacred Band's contribution to the battle was primarily in holding back a section of the Spartan army that was being sent to stop the maneuver long enough for it to be completed. As important as they were, they didn't do much that was particularly special that a different group couldn't have done. They helped them succeed through freedom to maneuver out of the line into an interception.
The Athenians were upset at the Thebans beating the Spartans' collective ass, and the Sacred Band was destroyed almost at their next major battle, the Battle of Chaeronea. They were elite infantry, yes, but the decision to make it up entirely of homosexual couples did little or nothing to increase their effectiveness compared to their training and individual skill (the Sacred Band was chosen among soldiers purely by merit and ability, with no regards to social class).
They were arranged as pairs of lovers because of the logic that no man would want to abandon his lover or look like a coward in front of him; while this certainly kept them from retreating or surrendering, usually you WANT your elite units to retreat instead of letting themselves be ripped to shreds in a glorious but ultimately useless last stand. Despite the legends of groups like the 300 Spartans, small groups of soldiers facing down groups numbering in the thousands tend to get crushed and ground up pretty quickly just under the sheer weight of the imposing army without making a battle-turning dent on their way out.
The story of love conquering the notoriously rough and dangerous Spartans may make for a good story, but their contribution to the battle primarily came from training and selection for individual ability that made them actual elites.