Bullmastiffs are a new breed relatively speaking, and were bred in the late 1800s to guard the estates of English landed gentry from poachers. (breedingbusiness.com)
They have been used to help guard estates and livestock, pull carts and sleds, as rescue dogs, and to serve in war. (dogs.animal-world.com)
Bull Mastiffs were originally an English breed used to guard estates from poachers. (lovethatpet.com)