My aunt had a horse named Mariah. That pony was 13-14hh. When my aunt was putting a gelding in a field, she had to go through a field with a stud in it. Well, the stud didn't like geldings so he came charging to kill this gelding. My aunt was trapped in-between and her mare Mariah came flying to protect her owner. That pony fought off a 16hh stallion. She kept kicking at him when her got close and she walked with my aunt till she got to the other field. When my aunt released the gelding she looked neck and saw her mare trotting off as nothing had happened.I would definitely call that protective!