It's a few years after the end of DAWN. Caesar and his village of apes have been on the run from a military group run by the Colonel (Woody Harrelson). It was Koba who began the war and Caesar wants to stop it and simply leave in peace. Not only are human soldiers after them with modern weaponry, they are being helped by those apes that were a part of Koba's revolt. Now those traitors are little more than slaves, branded, and referred to as "Donkeys". When the Colonel takes things too far Caesar goes on a mission of revenge, accompanies by three of his ape companions. Along the way they pick up a mute human girl and encounter another ape who has survived by himself at was once a zoo. The Colonel is so determined to wipe out the apes because he believes there's only room for one intelligent species on the planet. And also because the "Simian Flu" has further mutated, causing humans to become mute.
There are enough references and situations to BENEATH THE PLANET OF THE APES that WAR qualifies for a "re-imagining" of that original film. And like BENEATH it has a downbeat ending with a lot of death and destruction. However, there are survivors, among them Caesar's son Cornelius, so I'm guessing that the next film will be a version of the first POTA movie, with Cornelius encountering astronauts returning from Mars (which was hinted at in RISE). Highly recommended.