which war was the main antagonist involved in?
War of the Last Alliance.
Sauron
Led by Elendil, nine ships carrying faithful Númenóreans were saved from the Downfall; they founded the kingdoms of Gondor and Arnor in Middle-earth. Sauron returned to Mordor; Mount Doom again erupted. Sauron captured Minas Ithil and destroyed the White Tree; Isildur escaped down the Anduin. Anárion defended Osgiliath and for a time drove Sauron's forces back to the mountains. Isildur and Anárion formed an alliance and defeated Sauron at Dagorlad. They invaded Mordor and laid siege to Barad-dûr for seven years. Sauron was killed by Gil-galad and Elendil, who perished in the act. When Elendil fell, his sword Narsil broke beneath him. Isildur took up the hilt-shard of Narsil and cut the One Ring from Sauron's hand, vanquishing Sauron. Elrond and Círdan, Gil-galad's lieutenants, urged Isildur to destroy the Ring by casting it into Mount Doom, but he refused and kept it for his own.
who has a ring of power in lotr Sauron. who is he/she? The title character and the main antagonist of "The Lord of the Rings". is it a series or a novel? A novel in three volumes. who is the author of this novel? J. R. R. Tolkien. has it been adapted in any form? It  has been adapted for film, radio, stage, and television.
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Sauron [SEP] War of the Last Alliance
Led by Elendil, nine ships carrying faithful Númenóreans were saved from the Downfall; they founded the kingdoms of Gondor and Arnor in Middle-earth. Sauron returned to Mordor; Mount Doom again erupted. Sauron captured Minas Ithil and destroyed the White Tree; Isildur escaped down the Anduin. Anárion defended Osgiliath and for a time drove Sauron's forces back to the mountains. Isildur and Anárion formed an alliance and defeated Sauron at Dagorlad. They invaded Mordor and laid siege to Barad-dûr for seven years. Sauron was killed by Gil-galad and Elendil, who perished in the act. When Elendil fell, his sword Narsil broke beneath him.