In the Third Age, Sauron arose again in TA 1000, at first in a stronghold called Dol Guldur, the Hill of Sorcery, in southern Mirkwood TA 1050. There, he was disguised as a dark sorcerer known as the Necromancer, and the Elves did not realize at first that he was actually Sauron returned. The wizard Gandalf went to Dol Guldur in TA 2063in secret to see who it was that ran Dol Guldur but Sauron, sensing that his secret identity was about to be unveiled, had fled before him and gone into the East to hide; thus began the Watchful Peace. Sauron returned in TA 2460. Gandalf the Grey stole into Dol Guldur in TA 2850 and discovered the truth. Eventually, the White Council put forth their might and drove Sauron out in TA 2941. Without the Ring in his possession, Sauron could draw on only the smallest fraction of its strength, so that his enemies were able to drive him from Dol Guldur with relative ease. The Dark Lord, having had ample time to prepare, simply returned to Mordor and rebuilt Barad-dûr. Here, Sauron prepared for the final war against the free people of Middle-earth.
Sauron bred immense armies of Orcs and allied with and enslaved Men from the east and south. He gathered his most terrifying servants, the Nazgûl (airi in Quenyan), or Ringwraiths, each wearing one of the nine rings designed for mortal men. He adopted the symbol of a lidless eye, and was able to exert his will over Middle-earth, so that the Eye of Sauron became a symbol of power and fear. While Sauron did have a physical form, he remained much weakened without the One Ring and remained hidden in the shadows, directing his armies from afar.