§ Of the Rings of Power and the Third Age The Silmarillion

But Isildur was overwhelmed by a host of Orcs that lay in wait in the Misty Mountains; and they descended upon him at unawares in his camp between the Greenwood and the Great River, nigh to Loeg Ningloron, the Gladden Fields, for he was heedless and set no guard, deeming that all his foes were overthrown. There well nigh all his people were slain, and among them were his three elder sons, Elendur, Aratan, and Ciryon; but his wife and his youngest son, Valandil, he had left in Imladris when he went to the war. Isildur himself escaped by means of the Ring, for when he wore it he was invisible to all eyes; but the Orcs hunted him by scent and slot, until he came to the River and plunged in. There the Ring betrayed him and avenged its maker, for it slipped from his finger as he swam, and it was lost in the water. Then the Orcs saw him as he laboured in the stream, and they shot him with many arrows, and that was his end. Only three of his people came ever back over the mountains after long wandering; and of these one was Ohtar his esquire, to whose keeping he had given the shards of the sword of Elendil.