A retired officer of the Rohirrim when the invasion of Rohan began during the War of the Ring, he was the chief lord of Westfold and the Hornburg.

As was his duty, he assumed command of the West-mark after Théodred’s death during the First Battle of the Fords of Isen. Command of those forces already at the Fords he gave to Grimbold, until he himself could join the battle after assembling more forces from Westfold.

After the Second Battle of the Fords of Isen, he regrouped his forces, and returned to Helms Deep during the Battle of the Hornburg, just as King Théoden led a cavalry charge straight into the enemy hosts of Isengard.

With Erkenbrand, Gandalf, and Shadowfax leading the way, a thousand men on foot armed with swords charged down the hills, effectively trapping Saruman’s army of Dunlendings and Orcs. Though the Dunlendings surrendered, the Orcs fled into the newly formed forest of the Huorns, never to emerge. Thus ended the battle of Helms Deep.

After the War of the Ring, King Éomer granted Erkenbrand the title of Marshal of the West-mark.