Annatar had been the one who taught the Elven-smiths, led by Celebrimbor, how to forge the Rings, whilst, in secret, he forged his own One Ring in the fires of Mount Doom, a Ring far more powerful than any of the others. However, in order for the One Ring to be powerful enough to control the other Rings, Sauron had to transfer most of his power into it. As soon as he put it on, the elves became aware of his ruse, removing and hiding their Three Rings, which Celebrimbor had forged without Sauron's aid. Sauron waged war on the elves, conquering much of Middle-earth and killing Celebrimbor. Thus began the Dark Years, when Sauron took possession of the remaining sixteen Rings, giving seven to the dwarves and nine to men in an effort to corrupt them. The dwarves proved relatively immune to the powers of the Rings, acquiring only a greed for gold, and becoming unconcerned with events in the wider world. Men proved less resilient, and the nine kings given the Rings become the nine Ring-wraiths, or Nazgûl, led by the Witch-king of Angmar. In his ongoing efforts to conquer Middle-earth, Sauron regained the allegiance of many of Morgoth's servants from the First Age, and successfully corrupted Númenor. However, in doing so, he expended a great deal of his power, and lost the ability to ever again assume a pleasing disguise. Returning to Mordor, he regained his strength, eventually capturing Minas Ithil. However, realizing that if they did not join together, Sauron would destroy both men and elves, Elendil, High-King of Arnor, and Gil-galad, High-King of Noldor, formed the Last Alliance of Men and Elves, and attacked Sauron in his fortress, Barad-dûr. The alliance was victorious, with Isildur cutting the One Ring from Sauron's hand. However, although presented with a chance to destroy the Ring forever, Isildur, already beginning to succumb to its corruption, chose not to do so. As such, although Sauron's physical form was vanquished, his spirit, bound to the Ring, survived. Some time later, Isildur was attacked and killed by a band of orcs, and the Ring was lost in the river Anduin for over two thousand years. Meanwhile, during the Third Age, a still weakened Sauron covertly established a stronghold at Dol Guldur. In response to this undetermined evil, the Valar sent five Maiar to Middle-earth. Taking the form of wizards, they were led