Helm’s Deep was a deep gorge below the Thrihyrne near the end of the northernmost arm of the White Mountains on the far side of the Westfold Vale, which was named after Helm, the ninth King of Rohan.
Description
The deep gorge was located below the Thrihyrne at the head of the Westfold Vale. Caves, such as the Glittering Caves were located in the cliff walls of the gorge. The lower entrance of the gorge, Helm's Gate, was fortified by the Deeping Wall and the Hornburg. A quarter of a mile below Helm's Dike, a high rampart made from earth behind a trench ran across the Deeping-coomb from one side of the valley to the other side. The Deeping-stream flowed through the gorge through a culvert at the base of the Deeping Wall, turned to flow along the feet of the Hornburg down to Helm's Dike where it flowed through a wide breach in the rampart down the Deeping-coomb and into the Westfold Vale. The distance from the mouth of the Deeping-coomb to the Fords of Isen was approximately five leagues (15 miles) for the crows of Saruman.
Maps
In the long distant days of the glory of Gondor, at the height of their power, the Númenórean sea-kings of Gondor built a fortress at the entrance to the gorge, which they called the fortress of Aglarond, which means "Glittering Caves" in Sindarin. As a consequence, it is probable that Men from Gondor had already explored the gorge and its caves and named the fortress after the Glittering Caves.
When Steward Cirion of Gondor granted the province of Calenardhon to King Eorl of the Éothéod (later referred to as the Rohirrim), the fortress of Aglarond was repaired with the help of stonemasons from Gondor and handed over to the Rohirrim and the old hereditary guards of the fortress were transferred to the fortress of Angrenost, which remained under the control of Gondor. The Rohirrim called the fortress the Súthburg and the caves Glǽmscrafu in their own language.
During the war against the Dunlendings and Wulf's usurpation of Rohan, Helm Hammerhand took refuge in the keep, where they held out under siege during the Long Winter of T.A. 2758–2759. After Helm’s death, the gorge was called Helm's Deep and the fortification was called the Hornburg.
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.
Artwork
Helm's Deep
John Howe