Downfall of Barad-dûr

Sauron's Dark Tower of Barad-dûr was originally built over a period of centuries in the middle of the Second Age. Its foundations in the rock of Mordor were forged through the power of the One Ring, but nevertheless the Tower fell twice to Sauron's enemies.

At the end of the Second Age, after Sauron began an assault on the newly founded land of Gondor, Elves and Men formed a Last Alliance in opposition to Sauron. After defeating Sauron's forces in the Battle of Dagorlad, they set the Siege of Barad-dûr, and after seven long years, they eventually defeated Sauron himself and razed the Dark Tower. This first Downfall was not complete, because the Ring remained whole, and therefore Barad-dûr's foundations could not be destroyed.

More than three thousand years later, at the end of the Third Age, Sauron had risen again, but neither Elves nor Men had a fraction of the power they held at the time of the first Downfall of Barad-dûr. Unable to defeat their enemy through strength of arms, their strategy in the War of the Ring was to send the Ring by stealth into the heart of Mordor, and destroy it in Orodruin where it was forged. Despite Sauron's great military advantage, this plan succeeded: with the destruction of the Ring, the foundations of Barad-dûr failed, and the Dark Tower met its final Downfall.