Isildur, the son of Elendil, returned to Gondor after the fall of Sauron and remained there for a year. Unbeknownst to many in this context – Sauron was at the time diminished but not destroyed.
As a man of great pride and vigor, he had become the King of Arnor, as well as proclaim his sovereign lordship over the Dúnedain in the North and South.
Disaster of the Gladden Fields
Since he had left his wife and sons in Imladris, and wanted to seek counsel from Elrond, he had desired to go there first. Thus, he would go from Osgiliath up the Vales of Anduin, to Cirith Forn in Andrath, which would lead him down to Imladris.
Additionally, he also went with his sons Elendur, Aratan and Ciryon, and his Guard, to their journey where they would pass Greenwood the Great into the wide and empty lands.
Soon after, they would pass the Gladden Fields, which led to Thranduil’s realm in Mirkwood before hearing some cries of orcs, and would find out that Sauron’s vengeance still lived on even after the fall.
Isildur would be shocked to hear that the enemy was not withdrawing towards the forest as he once thought, when the orcs showed intense cunning, fierceness and hatred.
Elendur sought Isildur, for he was not yet harmed.
“My king,” [he said], “Ciryon is dead and Aratan is dying. Your last counsellor must advise, nay command you, as you commanded Other. Go! Take your burden, and at all costs bring it to the Keepers: even at the cost of abandoning your men and me!”
Isildur went west, and drew the Ring that hung in a wallet from a fine chain about his neck – and put it on and was never seen again for a while.
Thus, Elendur, who was supposed to have become King – had perished after the fall of the Dúnedain.
Isildur was in great pain and anguish, though he went to the banks of Anduin and suddenly he knew that the Ring had gone. He went into the river, and found out that it had left his hand – unbeknownst to him, thus he wouldn’t know where to find it again.
A great pain had been taken away and he was free from it. Then the Orcs found him and had him slain.
His line and legacy continued when his youngest son, Valandil, became the King of Arnor.
Aftermath (Council of Elrond)
It was revealed later in the War of the Ring, that the Ring had been found close to the edge of the Gladden Fields.
The Ring was supposed to have been cast into Orodurin’s fire, but Isildur would not listen to the counsel he had received.
Valandil would later remain in Rivendell, and Sauron’s Ring was lost but not unmade. This marked the Victory of the Last Alliance.
The Men of Westernesse were diminished, and their city, Annúminas, aside Lake Evendim, fell into ruin, and the heirs of Valandil were removed and dwelt at Fornost.
The Realm of Gondor long endured in the South, and for a while it looked similar to Númenor. Osgiliath was their chief city, and the people had built Minas Ithil and Minas Anor.
A white tree grew there, which was from the tree that Isildur brought over the deep waters and the seed came from Eressëa. This tree withered after the line of Meneldil son of Anárion failed, and Minas Ithil became Minas Morgul after it became a place of dread.
But the Lords of Minas Tirith still fought on, and kept the passage of the River from Argonath of the Sea – defying their enemies. The Days of Isildur the Ruling Ring had passed out of all knowledge, and the Three Rings were released from its dominion. The One Ring has been found again.