Battle of the Gladden Fields:
The battle of the Gladden Fields was fought between orcs, guarding
the area from retreating Dúnedain after the War of the Last Alliance
and Isildur, with a small guard. Isildur was heading north towards
the passes of the Misty Mountains and Rivendell. He was ambushed
with a small guard. They managed to survive the day, but that evening,
Isildur, wearing the Ring, attempted to swim the Anduin. The Ring
slipped off his finger and he was seen by the orcs. He was shot
by their arrows and killed. However, as was later found, the area
where they were was not very deep, about shoulder deep on a tall
man, and fairly slow-running.
There are at least two different traditions recorded about the Battle of the Gladden Fields, with the other stating that they were surrounded by a great host of orcs and overthrown. I believe the first tradition, as it was borne out by fact, as they found some artifacts of Isildur's death in Orthanc after. Only three men made it to Rivendell, including Ohtar, with the shards of the Narsil.
The Unfinished Tales