Boromir II was the son of Denethor II and next in line to be the steward of Gondor. In 3018 he defended the stronghold of Osgiliath against the servants of Sauron, and later that year went to Rivendell to attend the Council of Elrond and find out why he and his brother had had the same dream. He became one of the Companions of the Ring, though he had always had a desire not to destroy the Ring, but to use it. Upon Amon Hen the calling of the Ring became to strong for him, and he attempted to take it from Frodo with force. His attempt failed. Boromir was slain defending Merry and Pippin, and his body was sent afloat down the Anduin.
Boromir had always been overly proud as the heir to the stewardship of Gondor, and many believe that this is what forced him to attempt to sieze the Ring.