Capture
Grrrrrooolll!!! Chiiwwikk!!
Retreating with the backs facing the enemy would always be the worst part of any battle. Not only would the enemy charge at the retreater like a lunatic as they could see the glorious win, those retreating would also be prone to letting go of all inhibitions as they could see the horrid defeat.
Hence, it was known in almost any battle that such a particular move was exactly the time where the casualty number was the highest.
In modern day on Earth, such a similar occurrence would normally be followed with the winner giving a restrain and showing mercy.
However, for Tristan and these green-skinned orcs, such a rule was pretty much nonexistent. Hence, the reason for the current sight.