First Marshal of the Riddermark

The First Marshal of the Riddermark was the highest military rank among the Riders of Rohan. Unlike the Second and Third Marshals, whose duties were assigned as the times demanded, the First Marshal always had the same responsibility: he commanded the Muster of Edoras, i.e. the Riders of the capital Edoras and the surrounding lands, including the King's Lands and Harrowdale.
In his youth, King Théoden had led the Riders of the Muster of Edoras himself, so that no First Marshal was needed. When the King later fell under Saruman's power, Gríma Wormtongue worked to ensure that no First Marshal was appointed, leaving a vacuum of power for him to exploit, and at the time of the War of the Ring, there was no First Marshal of the Riddermark.