Apocalypse Now is a 1979 American epic war film directed, produced and co-written by Francis Ford Coppola. It stars Marlon Brando, Robert Duvall, Martin Sheen, Frederic Forrest, Albert Hall, Sam Bottoms, Laurence Fishburne, Harrison Ford, and Dennis Hopper. The screenplay, co-written by Coppola and John Milius and narration written by Michael Herr, was loosely based on the 1899 novella Heart of Darkness by Joseph Conrad. The setting was changed from late 19th-century Congo to the Vietnam War. The film follows a river journey from South Vietnam into Cambodia undertaken by Captain Benjamin L. Willard (a character based on Conrad's Marlow and played by Sheen), who is on a secret mission to assassinate Colonel Kurtz (Brando, with the character being based on Conrad's Mr. Kurtz), a renegade Army Special Forces officer accused of murder and who is presumed insane.
Milius became interested in adapting Heart of Darkness for a Vietnam War setting, and initially began developing the film with Coppola as producer and George Lucas as director. After Lucas became unavailable, Coppola took over directoral control, and was influenced by Werner Herzog's Aguirre, the Wrath of God (1972) in his approach...
Definition from Wikipedia – Apocalypse Now