In England, the Earl Marshal is the King's Marshal, in charge of the summoning of the feudal army (ie. the marshalling of the forces). Later, the Earl Marshal also became the final authority on matters of heraldry and eventually the head of the English College of Arms once it was established. Prior to this there had been Kings of Arms with no one of them expressly senior.
The SCA Earl Marshal
The title is also used at the Kingdom level for the senior marshal, responsible for all combat activity in the Kingdom. All marshals in the kingdom act with his authority and under his guidance. He is one of the key authorities if any reviews or changes are to be made to the Kingdom or Society's rules of combat.
At the local level, his subordinates are usually termed Knight Marshal for heavy fighting, and Rapier Marshal, Archery Marshal or Captain of the Archers, and Thrown Weapons Marshal or Thrown Weapons Captain for those fields.