Dr. W.F. Dove made quite a splash with his "Unicorn Bull" in 1933. He was a biologist at the University of Maine, and was experimenting with trying to create a unicorn bull. What he did is he took a calf, and he removed the tissue parts that would become its horns and transplanted them to the center of the forehead.
Dr. Dove's experiment was a success, and the bull grew a massive horn in the middle of its forehead. The growth had some unexpected consequences. Reports say that the animal was able to recognize the power of having a single horn. This allowed him to pass under fences and barriers and a way to more easily reach in it's attacks. These benefits also had another consequence, it was actually pretty mild mannered. The bull knew how much of a beast it was, and therefore didn't need to prove anything to anyone.