Disaster of the Gladden Fields
The Battle of Gladden Fields was an ambush on Isildur and his personal guard. During the last stand, Isildur put on the One Ring and tried to swim the Anduin. But the Ring slipped off his finger as he swam, and as he rose out of the water in the moonlight prowling Orcs shot him. Only two of the ambushed survived, one of which was his esquire which brought the shards of Narsil to Rivendell.