Origins and Names
The oldest attested name for the mountain, Orodruin, is Sindarin, built from the element orod, meaning mountain, joined to a second element denoting blazing or ruddy fire. Tolkien's own glossary of Elvish name-elements renders the compound as something close to Mountain of Blazing Fire, a description drawn from the peak's volcanic nature rather than from any deed connected to it. This appears to have been the name current among the Elves, and it is the form generally favored in learned or formal speech by those versed in the older tongues.
A second Sindarin name, Amon Amarth, came into use later, when Sauron himself renamed the mountain after its long-dormant fires stirred again in the Second Age. Amon means hill, and amarth means doom or fate, so the name reads as Hill of Doom, a title of foreboding that Sauron is said to have pronounced in wrath, at a time when his dealings with the Elves over the Rings of Power had turned to open enmity. It is this name, rather than Orodruin, that passed into Westron as Mount Doom, the form by which the mountain became known far beyond Mordor's borders.
Within the narrative proper, both older names remain current: Gandalf and Elrond speak of Orodruin when discussing the mountain's fires and the making of the Ring, while Mount Doom is the term used by Frodo, Sam, and the narration of the story's later chapters. English narration also employs purely descriptive epithets, calling it the Mountain of Fire or the Fiery Mountain, phrases that convey the sense of the Elvish names rather than translate them formally. By the close of the Third Age, Mount Doom had become the name in ordinary use among Men and Hobbits, while Orodruin persisted chiefly as a learned or ceremonial form.
Land and Place
Mount Doom rises alone on the ash-grey plain of Gorgoroth, in the western reaches of Mordor, set apart from the mountain walls that hem the land in on almost every side. The Ephel Duath runs along the west and south, the Ered Lithui along the north, and between these ranges the plain lies bare and blasted, broken by little but the works Sauron raised there and the mountain itself. Because Mordor's encircling peaks close the land off like the walls of a fortress, Mount Doom stands roughly at its heart, a single dominating landmark visible across the open waste to anyone who ventured that far.
From its lower slopes the walls and towers of Barad-dûr could be made out across the plain, for Sauron had set his stronghold within Mordor close enough to keep the mountain always under watch and within easy reach of the roads and camps that served it. Mountain and tower thus stood as the twin centres of the guarded land, linked by tracks that ran between them over the otherwise trackless ash, so that neither could be approached without passing near the other.
The mountain itself takes the form of a great cone, its long lower skirts spreading wide over the plain before the slopes steepen toward a smoking summit. Its flanks are grey with ash and scored by old scars where fire had once run down them, bare of any green thing and forbidding to climb by nature alone. A road built long before by labour driven to the task winds up from the plain and about the cone's shoulder, mounting gradually toward an opening near the top; it is the one made way onto the mountain, the rest of its slopes being left to loose ash and broken rock.
History
Sammath Naur, the Chambers of Fire hollowed into the mountain's cone, became the place of Sauron's greatest working around the year 1600 of the Second Age. Withdrawing there from Barad-dûr, then still under construction, he poured a great part of his own inherent power into the working of the One Ring, so that the mountain's fire and the Ring's substance were bound together from the outset. The act had a lasting consequence: because the Ring had been tempered in that fire, no other flame in Middle-earth was hot enough to unmake it, a fact that would govern the mountain's fate for the rest of the age.
When the Elves and the Men of the Last Alliance marched against Sauron at the end of the Second Age, the war that followed ended in sight of the mountain's slopes, where Sauron was overthrown and the Ring cut from his hand by Isildur. Elrond, who had stood among the victors, later recalled that he and Círdan urged Isildur to cast the Ring into the fire of Orodruin then and there, while the way to Sammath Naur still lay open before them, so that Sauron's power might be ended for good. Isildur refused, keeping the Ring as a weregild for his father and brother, and the mountain's fire was left unspent for the destruction it alone could accomplish.
For long ages afterward Orodruin lay quiet, its fires banked while Sauron's spirit wandered dispossessed of body and Mordor stood largely untended. The mountain stirred again only when Sauron, having regathered his strength in Dol Guldur, openly returned to Mordor and refortified Barad-dûr, an event the loremasters placed in the middle of the twenty-ninth century of the Third Age. Its rekindled smoke and glow, visible by night even from beyond Mordor's walls, became a sign read by the watchful, among them Gandalf, as confirmation that Sauron had taken up his old seat of power once more.
The mountain's history reached its crisis during the War of the Ring, when Frodo and Sam, guided over the last miles by Gollum, struggled up the winding track to Sammath Naur in March of the year 3019 of the Third Age. There, at the very brink where the Ring might have been unmade, Frodo claimed it for his own rather than destroying it; it was Gollum, seizing the Ring and Frodo's finger together in a final struggle, who fell into the chasm of fire and so brought about the Ring's unmaking. The mountain answered at once with a violent eruption, its chamber collapsing and its slopes running with fire and ash as the force bound into the Ring since its forging broke loose.
The eruption that consumed Sammath Naur coincided with the fall of Barad-dûr and the final ending of Sauron's power, so that the mountain's last violent act closed the story it had opened in the Second Age. Frodo and Sam, driven out onto a shoulder of the cone by the rising fire and ash, were carried to safety from the mountain's slopes by Gwaihir and other eagles sent at Gandalf's asking, narrowly outpacing the flood of lava below. No further eruption or awakening of Orodruin is recorded after that day, and the tale leaves the mountain, like the land around it, to the long quiet that followed Sauron's downfall.
People and Rule
No people held Mount Doom as a homeland, and no line of kings or chieftains governed from it in the way lesser lords ruled the settled regions of Middle-earth. For as long as any record reaches, authority over the mountain belonged to whoever commanded Mordor as a whole, and from the time Sauron made that land his own until his final overthrow, that authority was his alone. Unlike the wider realm, which he governed through Orcs bred to his service and through Men of the East and South drawn or coerced into his allegiance, the mountain itself he kept as the private seat of his own working rather than a domain administered through subjects.
Those who came onto its slopes did so as guards or labourers acting under that single authority, not as settlers in their own right. Companies of Orcs drawn from the garrisons of Mordor kept watch along the mountain road and across the plain below, a patrol that Frodo and Sam briefly joined unnoticed while disguised in Orc-mail on their approach toward Sammath Naur. Overhead the Nazgûl ranged as Sauron's most trusted servants and the instrument of his will stationed nearest the mountain; the instant he perceived the Ring claimed at the Crack of Doom, it was they whom he sent flying toward Orodruin, a last exercise of the direct rule he held over the place until the very end.
The mountain's only neighbor of real consequence was Gondor, whose kings and stewards contended with Sauron's realm through the whole of the Third Age without ever holding ground close enough to threaten Orodruin itself; even at the height of their strength they disputed no more than Ithilien and the passes of the Ephel Duath, and after the fall of Minas Ithil their hold on that border receded still further. The relationship between the two realms was accordingly one of siege rather than shared rule: Gondor bounded and watched Mordor from without, while within its walls Mount Doom answered to no one but Sauron until the day his power was broken.
Role in the Story
For most of the tale Mount Doom exists as an idea before it exists as a place: the smoking peak invoked at the Council of Elrond as the only fire that can undo the Ring, and thereafter the fixed point toward which the entire quest bends. Its distance measures the story's despair as much as its geography. Every setback on the journey through Emyn Muil, the Dead Marshes, and Ithilien is felt against the mountain's remoteness, and every glimpse of its glow on the horizon reminds Frodo and Sam how far they still have to go. The mountain functions less as a destination to be reached with relief than as a weight that grows heavier the closer the bearer comes to it, since the Ring's own pull on Frodo intensifies in direct proportion to Sammath Naur's nearness.
In the final chapters the mountain becomes the stage for the story's central irony: the one place built and fortified to keep the Ring safe for its maker is also the only place able to destroy it, and the tale's resolution depends on that contradiction rather than on the strength or virtue of those who arrive there. Frodo's failure at the very brink, after carrying the burden across the whole of the narrative, denies the story a straightforwardly heroic climax; it is Gollum's fall, born of the same fixation that drove him there, which closes the plot the Fellowship set out to close. Mount Doom thus stands less for triumph achieved than for an ending secured despite the failure of will it was designed to test.
Beyond Frodo and Sam, the mountain draws other threads of the story to a single point at the same hour: Aragorn's diversion at the Black Gate is staged expressly to hold Sauron's attention away from it, and Sauron's own final gesture, hurling the Nazgûl toward the summit the instant he senses the Ring claimed, shows how completely his strategy had come to hinge on that one location. When the mountain erupts, its collapse is felt simultaneously as the unmaking of the Ring, the fall of Barad-dûr, and the rout of Sauron's armies, so that a single volcanic event carries the weight of every plot line the book has been advancing. Few places in the narrative are made to bear that much convergence at once.