We did have an incident when a new lease horse was added to the herd years ago. He had a studly attitude and the two mares and one gelding chased him and cornered him, then the two geldings had an all out stallion fight. Boss mare gets others to do her dirty work.
She did get mad one day when everyone was let out of the stalls to go through the dry paddock and out to graze. The others went out first and left her in the stall. She tore out, rounded them up and ran them back to the paddock. She then calmly walked out to graze and it was some minutes before the others made a move to go out.