Durthang

Durthang was a fortress in the mountains of northern Mordor, and one of the many Orc-holds along the northern mountains there. 
It stood in the northern Ephel Dúath, on the slopes above Udûn and the Isenmouthe, which it in part watched over.
== History ==
It was originally built by Gondor after the War of the Last Alliance to keep watch on Mordor and prevent evil from entering there again. At first Durthang was like the other fortresses and castles built to watch over Mordor, fully maintained and manned. However, as Gondor's power began to decline, the fortress began to be neglected from the reign of Atanatar II. It was finally abandoned after the Great Plague that vastly depopulated Gondor and evil began to re-enter the formerly desolate land. The ruined fortress was repaired by Sauron upon his return to Mordor and was garrisoned by his forces during the War of the Ring.
Frodo and Sam passed this castle when they headed to Mount Doom as they had to go northwards and then south to avoid Barad-dûr, and they found this castle to be vigilant and hostile. The castle sent out Orc-forces to march to Udûn for the Battle of the Black Gate, the battle which ended the War of the Ring in the south-east. The exact fate of Durthang remains unknown.