Hiding of the Rings of Power by Celebrimbor
After Sauron created the One Ring and sought to take control of the other Rings of Power, Sauron never knew that Celebrimbor forged three more rings after Sauron departed from Eregion.
Celebrimbor and the elves of Eregion realized that Annatar was Sauron and Sauron manipulated them to forge the Rings of Power and take control of them with the power of the One Ring.
Celebrimbor quickly sent the Ring of Air Vilya and the Ring of Fire Narya to Gi-Galad in Lindon and sent the Ring of Water Water nenya to Galadriel.
While Celebrimbor held the other 16 rings to him(There are conflicts where Durin III, the king of Khazad-dum received one of the rings of power).
Beginning of the War of the Elves and Sauron
After Sauron gathered and trained his forces for a long time, Sauron launches a full-scale invasion to Eriador where Eregion and Lindon resided. Sauron’s forces would slip into the Gap of Rohan that was located between the far south end of the Misty Mountains and the White Mountains.
The Dunlendings that were forced out from Minhiriath and Enedwaith because of the Numenorian’s timber campaigns were occupying the lands of the Gap of Rohan. However, the Denlendings gladly gave way to the forces of Sauron so Sauron was able to secure passage for the march of his armies.
Fall of Eregion
Celebron has led a legion of the elves of Eregion and ward off the forefront of the forces of Sauron. However, Celeborn was eventually driven back by the numerous numbers of Sauron and had to retreat.
Gil-Galad of Lindon would appoint Elrond as the commander of the expeditionary forces of Lindon to relief Eregion. Gil-Galad would send word for aid to Numenor as well. Celeborn’s remaining forces of elves were able to join Elrond’s army of elves of Lindon.
However Sauron’s army has already sieged Ost-in-Edhil capital of Eregion and Elrond’s army with Celeborn couldn’t even reach Eregion because of the heavy resistance of Sauron’s army.
Sauron’s forces were too many in numbers and overwhelmed the forces of Elrond from Lindon and Elrond had to establish a defense at the Bruinen River in Imladris also known as Rivendell. By Sauron’s army Eregion has perished.
Capture of Celebrimbor and the Nine Rings and the Seven Rings
Celebrimbor led the last defense of Ost-In-Edhil, however Sauron’s army overran the capital of Eregion. Celebrimbor was captured and had to hand over the Nine Rings and the Seven Rings to Sauron.
Celebrimbor, however, was able to successfully hide the Three Rings as he had already sent them to Gil-Galad and Galadriel.
Sauron severely tortured Celebrimbor with cruelty, however Celebrimbor didn’t give up on the locations of the other Three Rings.
Sauron in fury and for in attempt to mock Celebrimbor, would severely torture Celebrimbor that killed him and display the corpse of Celebrimbor pierced on a spear.
Counterattack by the elves and dwarves
Durin III from Khazad-dum would send dwarves and attack the rear of Sauron’s forces while the elves of Loriand led by Amroth also attacked the armies of Sauron from the rear side.
The dwarves of Khazad-dum would evacuate the refugees of Eregion through the paths of Khazad-dum where the survivors would later settle in the lands of Lothlorien.
After the dwarves retreated to Khazad-dum, the dwarves would shutdown the Doors of Durin that was a symbol of friendship with the Noldor elves of Eregion and the dwarves of Khazad-dum
Imladris, Rivendell
Located by the gorge of the Bruinen River, Rivendell was a narrow-hidden land located on the west side of the Misty Mountains near Eriador. Elrond would establish a fortress in Rivendell in defense against the forces of Sauron.
Thanks to the support of the dwarves of Khazad-dum and Loriand elves, Elrond was able to evacuate the refugees of Eregion that fled north into Imladris.
As Sauron’s forces overwhelmed Eriador, more and more refugees headed to Imladris.
Siege of Imladris, Lindon and the Grey Havens
Sauron’s forces started to trample Eriador and eventually sieged Imladris, Lindon and the Grey Havens. Refugees of Eriador escaped to Imladris to the east or escaped to Lindon and the Grey Havens to the west.
Gil-Galad was able to hold the defense lines along the Lhun River, however more and more troops of Sauron assembled to finish off the remaining elves on Middle Earth.
Reinforcements of the Numenorians
The nephew of the queen Tar-Telperien of Numenor, Minastir(Later he would become the king of Numenor Tar-Minastir) have came to the rescue of the elves of Eriador with the military of the Numenor Kingdom. Tar-Minastir sent the armada of the Numenor navy under the command of Ciryatur to relief the siege of Eriador.
While the main forces of the Numenor army landed on Lindon, Ciryatur, the commander of the Numenorians split some of his forces to the harbors of Lond Daer.
The elf army with the reinforcements of the Numenorians were able to push through Sauron’s lines at Luhn River and Sauron had to retreat to the southeast.
Battle of the Gwathlo
The allied forces of the Numenorians led by Ciryatur and Tar-Minastir and the elf army of Gil-Galad tracked down the retreating forces of Sauron near Gwathlo.
Meanwhile the Numenorians that landed on the harbor of Lond Daer were also able to attack Sauron’s army from the southwest while Gil-Galad and Ciryatur’s main forces attacked from the north on Sauron’s army.
Sauron’s army was hit from the front and rear during their retreat and were almost annihilated where Sauron barely managed to escape back to Mordor.
Gil-Galad would later relief the Siege of Imladris and the Numenorians and elves won the War of the Elves and Sauron.
Sauron’s grudge against Numenor
Sauron nearly had the elves however his plan failed as Celebrimbor forged the three rings for the elves that were out of the control of the One Ring.
Also when Sauron almost conquered Eriador, the Numenorians that were direct descendants of the Edain humans also blessed with long life by the Valars ruined Sauron’s conquest. Sauron had to give up on his plans to corrupt the elves, and Sauron also pledged to take vengeance on the people of Numenor.
