Like the other five films in the series, Lord of the Rings: The Return of the King had a signature song play over its end credits. Previously selected was the song "Use Well the Days," until director Peter Jackson decided the song was tonally unfitting for the final entry in the series. Thus, he tasked composer Howard Shore with writing a new song.

Around this time, Jackson had learned that a teenage filmmaker named Cameron Duncan, whose work he had found impressive, had been stricken with terminal cancer and that his passing was soon to come. Taking inspiration from this young man, composure Shore, writer Fran Walsh, and singer Annie Lennox began to write "Into The West", adopting the somber yet comforting tone of someone approaching their death.

The song would go on to be one of the eleven Academy Awards won by the film. Its first public performance was at the funeral of Cameron Duncan.

More Info: en.wikipedia.org