What is the snaffle and rein of a military bridle, which acts independently of the bit, at the pleasure of the rider. It is used in connection with a curb bit, which has its own rein. Campbell called?

bridoon — The snaffle and rein of a military bridle, which acts independently of the bit, at the pleasure of the rider. It is used in connection with a curb bit, which has its own rein. Campbell. (Webster's 1913.)