The one I had is essentially the same thing with a few modifications (break away parts on the castle, balls instead of checkers) -- and instead of two castles firing at one another, one person would fire at the castle and the other would fire at soldiers positioned in attack formations set up on a cardboard layout they were fastened to.
It was called Weapons and Warriors and I am 90% sure I still have this one and the pirate one somewhere in my parent's basement.

