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At the time of the War of the Ring, Helm’s Deep became the refuge of some of the Rohirrim under King Théoden. The keep fell under siege and was breached by Saruman’s Uruk-hai, and subsequently the Battle of the Hornburg was fought.

After the battle, someone, probably the Huorns, laid the slain Uruk-hai in a mound known after as the Death Down. The Dunlendings allied with Saruman were buried more honourably in a separate mound below the Dike.