Reading a biography of Alexander the Great (Agnes Savill, Alexander the Great and His Time), I came across the following:

The famous Theban band [of male lovers] was renowned for its heroism; the lovers swore to live or die together and were invincible in war. To gain the admiration of his friend, a young man attempted deeds of valour; the praise of his companion was to him more precious than that of any relative or superior officer.

Not quite invincible, it seems. At the battle of Chaeronea on August 2, 338 B.C., the Greeks were arrayed against the forces of Philip of Macedon, Alexander's father. The Greeks' very independence was at stake, and both Theban and Athenian armies allied to defend it against Macedon. Key to the Theban military was the Theban Sacred Band, the group of 150 pairs of same-sex lovers Savill refers to above. For decades they had been considered the elite of the Theban army. Now they faced the better trained and more experienced Macedonian forces under Alexander's command. In hard-fought battle, the Sacred Band was decimated. Here Savill picks up the narrative again:

When Philip saw the bodies of the fallen lovers after the battle of Chaeronea, he exclaimed with tears: "Perish the man who suspects that these men ever did or suffered anything base."

It is an extraordinary moment: an enemy commander paying tearful tribute to the bravery of an opposing forced comprised of a group of homosexual lovers. Not for Philip, it seems, the peculiar modern American notion that homosexuality is incompatible with military service. Philip is defending the Theban Band against those — and there were such people and regions even in ancient Greece — who would condemn them as vile or disgusting for their very love. In fact, this is among the first times in recorded history that a person of Philip's stature championed the basic dignity and worth of same-sex couples. He speaks to us today, Valentine's Day, more than 2300 years later.