Conquest of the Planet of the Apes (1972)

Part four continues the circular narrative, showing the reasons for the bloody revolution that established the ape society as it existed in Parts I and II.
It's interesting that even years later some apes wore the colours of the suits given to them by man. With the emphasis on slavery being what it is, I like to think the filmmakers were aware of what that implies and didn't use it simply as a cheap and easy way to differentiate the ape types.
Conquest probably won't win any new fans on its own merits, but it ought to keep existing ones content. So unless you're already fully invested in the symbolism of the world, then you may want to give it a miss.

3 true colours out of 5

EDIT: the blu-ray has two versions of the film, a Theatrical Cut and a slightly longer Unrated Cut. The two versions differ in how the final act plays out. The Unrated cut is the one that's arguably the more memorable of the two.