“The vengeance of Sauron lives on, though he may be dead,” he said to Elendur, who stood beside him, “There is cunning and design here! We have no hope of help…”The Unfinished Tales
The Disaster of the Gladden Fields is the event that takes place after Isildur refused to cast the Ring into the fire. Just because Sauron had been defeated, does not mean the enemies were gone. Sauron’s armies lived on, the Orcs still caused a lot of trouble for the realm of Elves and Men. Isildur and his men and traveling to see Elrond. He is accompanied by his son’s Elendur, Araton, and Ciryun when they are set upon by a band of Orcs that were being commanded by Barad-Dur. Isildur knows their situation is dire and gives the broken sword, Narsil, the sword of Elendil to his esquire, Ohtar—who we know delivers this sword to Elrond and it is later remade.
When Isildur realizes he only has one option, he takes it. He tries to control the Ring. But he cannot summon the strength to wield it. All of his sons perish in the fighting and he flees to the river. Where he drops the Ring and where the Ring remains until Deagol discovers it over 2,000 years later. —But Deagol does not keep the Ring for long as he is murdered by Smeagol who later becomes Gollum.
There are only two survivors of Gladden Fields and that is Ohtar, Isildur’s esquire, and Estelmo, Elendur’s esquire. If they did not survive, the events following Gladden Fields may have been dramatically different.