Дело было приблизительно так.
Поначалу в южной части Мирквуда (который тогда назывался Зеленолесьем) был некий холм, называвшийся Amon Lanc, "Лысый холм". Обитали там эльфы Лоринанда под руководством Орофера . Задолго до войны Последнего Союза они, обеспокоенные слухами о возрастающей мощи Саурона, покинули те места.(5.5)
Но ещё во времена Исилдура холм упоминается как Амон Ланк и служит ориентиром на местности - это высшая точка возвышенности в юго-западной части Зеленолесья. (5.4.)
Также холм в разных текстах называется Dol Dugul, Dol Dughul, Dol Dugol и Dol Dughol (это вниманию тех, кто будет искать его по текстам).
Далее, в 1000 году 3 эпохи, плюс-минус, Саурон появляется в Средиземье и закладывает на холме Дол Гулдур укрепление, которое получает то же название, что и холм. (3.3.) 'Hill of Sorcery', "холм волшебства" (1.2.).
В 1100 году Мудрые обнаруживают, что кто-то чёрный и страшный отстроился на холме. Они предполагают, что это один из назгулов.
(3.1.)
В описании укрепления упоминаются башни (6.1.).
На момент раставания Кириона и Эорла холм именуется Дол Гулдур, причём это именно холм - Эорл говорит "холм, который вы называете Дол Гулдур".
На тот момент сам холм и его окрестности - место "нехорошее", "под тенью" и так далее. Там явно происходит какая-то деятельность тёмных сил.
Однако, о крепости никто из них не говорит. (5.3)
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Использованные материалы:
1. Сильм, "О кольцах власти и Третьей Эпохе"
1.1. Now of old the name of that forest was Greenwood the Great, and its wide halls and aisles were the haunt of many beasts and of birds of bright song; and there was the realm of King Thranduil under the oak and the beech. But after many years, when well nigh a third of that age of the world had passed, a darkness crept slowly through the wood from the southward, and fear walked there in shadowy glades; fell beasts came hunting, and cruel and evil creatures laid there their snares.
Then the name of the forest was changed and Mirkwood it was called, for the nightshade lay deep there, and few dared to pass through, save only in the north where Thranduil's people still held the evil at bay. Whence it came few could tell, and it was long ere even the Wise could discover it. It was the Shadow of Sauron and the sign of his return. For coming out of the wastes of the East he took up his abode in the south of the forest, and slowly he grew and took shape there again; in a dark hill he made his dwelling and wrought there his sorcery, and all folk feared the Sorcerer of Dol Guldur, and yet they knew not at first how great was their peril.
1.2. Dol Guldur 'Hill of Sorcery', fastness of the Necromancer (Sauron) in southern Mirkwood in the Third Age.
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2. LotR:
2.1. `There lies the fastness of Southern Mirkwood,' said Haldir. 'It is clad in a forest of dark fir, where the trees strive one against another and their branches rot and wither. In the midst upon a stony height stands Dol Guldur, where long the hidden Enemy had his dwelling. We fear that now it is inhabited again, and with power sevenfold. A black cloud lies often over it of late.
2.2. c. 1100 The Wise (the Istari and the chief Eldar) discover that an evil power has made a stronghold at Dol Guldur. It is thought to be one of the Nazgul.
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3. HoME 12-1
3.1.
"The Third Age"
c.1100. It becomes known to the Wise (being the chieftains of the Eldar and the Istari) that an evil power had arisen in Mirkwood and had established a stronghold on the hill of Dol Guldur in the southern forest. But it was still some time before they knew for certain that this was the shadow of Sauron himself and that he was awake again.
3.2. Notes
1. On the name Dol Dugul for later Dol Guldur see VIII.122. In the manuscripts of The Lord of the Rings it is always spelt Dol Dughul (replacing original Dol Dugol).
3.3. 1000- Sauron wakes again, and enters Mirkwood. Establishes a stronghold at Dol Dugul (1) and slowly grows.
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4. HoME 8-2
4.1. The name of Sauron's stronghold in Mirkwood remains Dol Dughol, the change to Dol Guldur being made at a very late stage.(8)
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5. UT:
5.1. But in the meantime the power of Galadriel and Celeborn had grown, and Galadriel, assisted in this by her friendship with the Dwarves of Moria, had come into contact with the Nandorin realm of Lorinand on the other side of the Misty Mountains. This was peopled by those Elves who forsook the Great Journey of the Eldar from Cuivienen and settled in the woods of the Vale of Anduin [The Silmarillion p.94]; and it extended into the forests on both sides of the Great River including the region where afterwards was Dol Guldur.
5.2. Amon Lanc, "Naked Hill",as the highest point in the highland at the south-west corner of the Greenwood, and was so called because no trees grew on its summit. In later days it was Dol Guldur, the first stronghold of Sauron after his awakening. [Author's note.]
5.3. Эорл - Кириону, при расставании:
For that must be on the east side of Anduin ever under the threat of Mirkwood, and at last must pass through the vale that is haunted by the shadow of the hill that you name Dol Guldur.
5.4. The rain lasted for four days; so when they came to the entrance to the Vales, between Lorien and Amon Lanc, Isildur turned away from the Anduin, swollen with swift water, and went up the steep slopes on its eastern side to gain the ancient paths of the Silvan Elves that ran near the eaves of the Forest.
5.5.
14 Long before the War of the Alliance, Oropher, King of the Silvan Elves east of Anduin, being disturbed by rumours of the rising power of Sauron, had left their ancient dwellings about Amon Lanc, across the river from their kin in Lorien.
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6. HoME 7-3
6.1. From beyond the Inland Sea of Rhun up the rivers east of Mirkwood, round the towers of Dol Dughul they poured through fen and forest to the banks of the Great River.
6.2. They were come to the Brown Lands, the Withered Wold that lay in a vast
desolation between Dol Dughul in Southern Mirkwood and the hills of Sarn-Gebir
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7. HoME 7-2
7.1. On the two sites of Dol Dugol (Dol Dughul) see p. 298. For the
emergence of the name Rhosgobel see p. 164.
7.2. They climb Cerin Amroth. Frodo says [read sees] Anduin far away a glimpse of Dol Dugol.(38) H[athaldir] says it is reoccupied and a cloud lowers there.
7.3. 'There lies the fastness of Southern Mirkwood,' said Hathaldir. 'For the most part it is a forest of dark pine and close fir - but amidst it stands the black hill Dol-Dugol, where for long the Necromancer had his [? fort]. We fear it is now rehabited and threatens, for his power is now sevenfold. A dark cloud lies often above it. [?? Fear of the time is] war upon our eastern borders.'
7.4.
Some other geographical features are slightly doubtful, but the western arm of the Misty Mountains across squares I 10-11 was probably a subsequent addition, and the vast region of highland between Mirkwood and the Sea of Rhunaer, together with the streams flowing from it into the Dead Marshes (N 16), almost certainly so. The original siting of the name Dol Dugol (M 15; see p. 296) probably had nothing to do with these highlands (at the first occurrence of the name on p. 178 Gandalf speaks of Sauron's 'older and lesser dwelling at Dol-Dugol in Southern Mirkwood'): faint traces of green colour suggest to me that originally Mirkwood extended much further to the South-east, covering L 15 and a good part of M-N 15 - 16, and that this region of the forest was erased. The hills that emerge onto N 15 from the area which I have left blank on Map II are also additional: this region will be discussed later in this chapter.
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