Sexual humiliation and rape of captured soldiers run
back to the ancient Greece (and probably farther), where
the rape of soldiers taken prisoners was common and
part of the propaganda to scare the other side.

Of course, their fate after that wasn´t pleasant
either: If not killed outright, slavery was a common fate
and the lifespan of average slave was low. A common
fate for a soldier taken prisoner by the Athenians was
to be sent to work in the mines. After view years they
were dead.