Quote from : The Great Hunt Book

When we Shienarans ride, every man knows who is next in line if the man in command falls. A chain unbroken right down to the last man left, even if he's nothing but a horseholder. That way, you see, even if he is the last man, he is not just a straggler running and trying to stay alive. He has the command,and duty calls him to do what must be done. If I go to the last embrace of the mother, the duty is yours. You will find the Horn, and you will take it where it belongs. You will.