James, that was harsh, this person obviously knew the basics and has been caught out, because they knew about the 1 square foot rule, and maybe their breeder is just dodgy. Sometimes it's hard to sex birds, especially if you're new and haven't seen the colours other than in photos before.
This person was either sold bad stock or was lied to by their breeder. I don't see any way in which they could have prepared for that by reading.
I would agree that the most likely cause is too many males, but it might be something else, i.e. bad stock. If you can give them more space and hiding places, it can only help. Also if you take out your known males and things calm down it is probably extra secret males. Of course, it could just be that the males you have got are mean ones, chasing and hurting the hens. Also, if nothing else works, try changing the ratio to maybe 7 hens per male, because that ought to leave them a few extra females and reduce fighting over them. If you're not worried about fertile eggs you could get rid of all the males.