Path of Glory (Stanley Kubrick, Kirk Douglas, 1957), and Patton (Francis Ford Coppola , George C. Scott, 1970) are notable examples of presenting a modern concept that I am not sure existed in any ancient popular war lore. Beside Lysistrata I would be curious if there are any other tales of a popular concept of soldiers being so psychology tortured by war to the point that a population and than the army itself realizes they do more harm than good.

tldr: What ancient societies recognized that it was not a good idea to execute "cowards" in battle and how aware were ancient societies that it even existed?