The Return of the King (1980)

This film adapts the final book of the Lord of the Rings Trilogy where the Hobbits, Frodo and Samwise, struggle through the barren land of Mordor to destroy the Ruling Ring in Mount Doom. At the same time, Gandalf and the others wage a desperate battle against the forces of Sauron at Minas Tirith, but Sauron seems to have the upper hand while the source of his power, the Ring, slowly threatens to corrupt its bearers.