The herd stallion probably thinks Racer was trying to challenge him.

I wonder if Racer will ever be a herd stallion?

The herd stallion galloped down from the hillock on which he had stood.

The herd stallion didn't need to look back to check their positioning.

He went down, and the herd stallion smashed his killers, but it wasn't enough.

The herd stallion was one of the last to die.

"I wonder if his herd stallion knew something when he gave it to him?"

There is usually one herd stallion, though occasionally a few less-dominant males may remain with the group.

The herd stallion seems to have much more control over them than he would if they were horses.

The herd stallion probably er was trying to challenge him.