Lets go with the traditional British Empire punishment for treason, better known as Draw, Hang, and Quarter. They'd tie 4 extremities to 4 different ropes, then machinery would force the ropes to tighten, all in different directions. He would essentially be pulled until his arms and legs dislocate. Then he would be sent to the gallows, and hung. Then they would mutilate the body by chopping it into four pieces, and package it and send it to the King, for his enjoyment/amusement.