A Band of Lovers by Graeme O'May

This must-read book shares the fascinating history of the Sacred Band of Thebes - an elite infantry unit in Ancient Greece. The most capable fighting force of its time, it was uniquely comprised 150 male couples. Formed in the aftermath of Thebes' liberation from Spartan occupation in early 378 BCE, the Sacred Band inflicted on the Spartans their first-ever defeat by a numerically inferior force at the battle of Tegyra in 375 BCE and was instrumental in Thebes' astonishing victory at the epoch-making battle of Leuctra four years later. "A Band of Lovers" tells the story-the valor and accomplishments-of a truly remarkable army, and their influence was instrumental in the author's ability to overcome shame and finally accept his identity as a gay man.
In existence for a mere forty years, the Sacred Band was ultimately wiped out by Philip II of Macedonia, a military genius and father to Alexander the Great, at the battle of Chaeronea in 338 BCE. When defeat became inevitable, the men of the Sacred Band stood their ground, with their lives buying time enough for their comrades to escape and live on. After the battle, Philip, who'd lived in Thebes in the 360s, ordered the building of a monument to the men of the Sacred Band; the Lion of Chaeronea stands guard over their tomb to this day.