Perhaps oral traditions survive from soldiers sold into slavery from lost battles. Like somehow, the folly of volley fire made it into the name of some food dish.
Or maybe they would have simply massacred any army so dumb as to try it.
I don't understand the need to come up with some fancy niche (slavery, oral, food name) when you have the more common approach: as is usual, part of the army ran away, and it included people of all ranks, from soldiers to generals, and they recorded it in all the same ways all the other events for recorded in the same sources (including training guides)
Then you continue to ignore the other elephant - the soldiers and everyone else who won battles also record history avoiding the slavery/food route
Or maybe they would have simply massacred any army so dumb as to try it.