The Hornburg, located at the mouth of the gorge called Helm's Deep, was a great stronghold of Rohan. It housed the guards of the Fords of Isen, but was used in times of war as a sanctuary.
History[]
Said to have been built during the Second Age by the Men of Gondor, it was, along with Angrenost (Isengard), one of two strongholds built to guard the Fords of Isen. The fortress was turned over to the Rohirrim when the Steward Cirion handed control of Calenardhon to Eorl the Young. The remaining garrison was then redeployed to Isengard. The Rohirrim named the fortress Súthburg, as it was the southern fortress guarding the Gap of Rohan.
During the war with the Dunlendings under Wulf, the Rohirrim under King Helm Hammerhand and many of his people sought refuge in the keep, where they held out during the Long Winter of TA 2758 – TA 2759. After this heroic siege the fortress was renamed Hornburg in honour of Helm.
During the War of the Ring, the fortress again became the refuge of some of the Rohirrim, now under King Théoden, and the Battle of the Hornburg was fought there against Saruman's army. It was during this battle that the Deeping Wall was destroyed by explosives. Despite this, Saruman's forces were driven back and routed with the arrival of Erkenbrand on the morning of March 4, 3019.
The fortress was presumably repaired and strengthened by Gimli, Lord of the Glittering Caves that lay behind it.