War of the Elves and Sauron
The War of the Elves and Sauron was a great war fought in the Second Age.
The war began in 1693 S.A., almost a century after Sauron had deceived the Noldor of Eregion and had forged the One Ring. Sauron attacked Eregion, claiming all the Rings of Power from the fortress Ost-in-Edhil, except the Three Rings of the Elves.
In 1695 S.A. Sauron attacked, and Elrond was sent to Eregion by Gil-galad. However, in 1697 S.A. Eregion was laid waste. Celebrimbor, lord of Eregion, was killed, and Khazad-dûm's gates were closed. Elrond fled north with the survivors, founding Imladris (later Rivendell).
By 1699 S.A. all of Eriador fell under Sauron's control, and he set fire to the great forests in Enedwaith and Minhiriath to drive off the Elves and their allies (Edain). Imladris was besieged, and Lindon cut off from Imladris and Khazad-dûm.
The next year a great army of Númenor arrived, sent by Tar-Minastir, which landed in Lindon, at Tharbad on the Gwathló, and south near Pelargir. Sauron's forces were caught in between the armies, and destroyed. The war ended in 1701 S.A. when Sauron retreated to the east, but Eregion was gone, and most of Eriador destroyed.