In the original "Planet of the Apes" series, even though the latter three films depict world events chronologically prior to those of the first two films, the narrative itself is continuous for the main characters, as three apes from the first two films go back in time. The later installments "Escape from the Planet of the Apes" served as both a sequel and prequel to the first film. and "Battle for the Planet of the Apes") are sometimes called "prequels" in a broad sense of the word, but they are primarily sequels, as defined both broadly (as later installments) and narrowly (as continuation of the previously established storyline).