|这篇文章正在被编辑中，编辑完成前请不要同时编辑，以免撞车。你可以在这里找到正在施工的词条列表。编辑者签名:Fzz2004（讨论） 2018年2月22日 (四) 19:46 (CST)，本提示有效期15天，过期请协助解除。|
|“||There stood a tower of marvellous shape. It was fashioned by the builders of old, who smoothed the Ring of Isengard, and yet it seemed a thing not made by the craft of Men, but riven from the bones of the earth in the ancient torment of the hills.||”|
—— J.R.R. 托尔金
随着时间推移，艾森加德与米那斯提力斯之间的联系与通信越来越不频繁；宰相因为还拥有欧尔桑克的钥匙，他们越来越多地思考东方的事情。最后刚铎族长的血脉断绝，那里的人们更多地与黑蛮地人往来。他们甚至允许黑蛮地人进入艾森加德，最后两族自愿地融合为一体。后来艾森加德被黑蛮地人控制，他们在西伏尔德进行了很多次袭击。虽然洛希尔人没有足够的力量来攻击这处要塞，但黑蛮地人最后在漫长冬季后的大饥荒中因饥饿而屈服。因此，国王弗雷亚拉夫和宰相贝伦对萨茹曼接管艾森加德的请求很欢迎。于是，在第三纪元2759年，欧尔桑克的钥匙被给予这位巫师。 萨茹曼开始想要自己拥有魔戒，希望可以给索隆时间来重新积累力量来使它显露自身。作为白道会的领袖，萨茹曼在第三纪元2851年否决了甘道夫攻打多古尔都的请求。然而在第三纪元2941年，在萨茹曼发现索隆的仆从正在金鸢尾沼地搜寻魔戒时，他同意攻打索隆在黑森林的根据地。在第三纪元2953年白道会最后一次会议后，萨茹曼退回艾森加德并加固了这里。在大约第三纪元3000年，萨茹曼首次使用欧尔桑克晶石。于是索隆corrupted Saruman's mind and bent it to his will.
|“||Gandalf the Grey caught like a fly in a spider's treacherous web!||”|
在第三纪元2953年，甘道夫 rode to the foot of Orthanc and there met Saruman. It was then that Saruman revealed his true thoughts to Gandalf. He declared his desire to become a ruler of Men and to join with Sauron. But, most importantly, he announced his desire for The One Ring. Gandalf refused to submit to Sauron and Saruman. Subsequently, Saruman had Gandalf taken to the pinnacle of Orthanc where, Saruman schemed, Gandalf would stay until he reveal the location of the ring or until Sauron reclaimed it for himself. There Gandalf was trapped and for the first time he saw wolves and orcs in the valley of Isengard below. After many weeks of imprisonment,[note 1] Gandalf escaped as Gwaihir the Great Eagle came unlooked-for to Orthanc and bore him away.
On 2 March, T.A. 3019, the Ents of Fangorn Forest began their attack on Isengard. By the next day, the Ents have completely subdued Isengard.
However, their attacks on Orthanc proved futile because the rock of the tower was too hard for the Ents to damage. Therein Saruman remained. On 5 March, Théoden, Éomer, Gandalf, Aragorn, Legolas, and Gimli approached the foot of Orthanc and climbed its stair until they reached the door. There they parleyed with Saruman, who remained inside the tower and spoke to them from a balcony above the door. Saruman refused to co-operate and subsequently Gandalf cast him from the order of Wizards and the White Council, and broke Saruman's staff. After this confrontation, Gríma Wormtongue, who was also inside Orthanc, threw the palantír of Orthanc at the party outside as a parting shot.
A week before 22 August, T.A. 3019, when King Elessar and company arrived at Orthanc, Saruman had departed Isengard with Gríma Wormtongue. However, before he left, Treebeard made him lock the tower and hand over the keys of Orthanc.
One of King Elessar's first tasks in the re-ordering of his realm was the restoration of Orthanc. He ordered that the palantír recovered from Saruman should be returned to the tower. It was then that the tower was searched and many secrets were revealed. It became clear that Saruman had hoarded many ancient treasures and heirlooms. They found that, with the aid of Wormtongue, Saruman had acquired jewels and heirlooms of Eorl. With the help of Gimli a hidden door was found and opened. Inside a casket found on a shelf they found two precious items. One was a small golden case attached to a chain; this was used by Isildur to bear the One Ring. The second item in the casket was the Elendilmir, the "white star of Elvish crystal upon a fillet of mithril" that had been lost since Isildur's demise. Elessar recieved the Elemdilmir with reverence and took it with him as he established his full kingship of Arnor. It was clear that Saruman had found the remains of Isildur and that he had probably burned the body.
Orthanc and the lands of Isengard remained part of the Reunited Kingdom of Arnor and Gondor. However King Elessar granted the Ents complete self-governance of the area surrounding Orthanc. This new forest became known as the Treegarth of Orthanc.
Orthanc displays a curious double etymology (co-existing "by design or chance") since it has a meaning both in the "language of the Mark of old" (rendered as Old English in The Lord of the Rings) and Tolkien's constructed language Sindarin. Tolkien regarded this coincidence as an 'accident'.
In Old English, Orthanc is said to mean "Cunning Mind". Hammond and Scull has noted that Old English orþanc as a noun means "original, inborn thought" or "a skilful contrivance or work, artifice, device, design"; as an adjective it means "cunning, skilful". Cf. the meaning of Saruman's name "the one of cunning devices" or "Man of Skill".
In the published text, Orthanc is said to mean "Mount Fang" in Elvish. In other sources, the name is glossed as "forked-height". The name is likely supposed to be Sindarin, consisting of or + thanc.