Planet of the Apes Omnibus 1

When men discovered that the Planet of the Apes was their own Earth, it was only the beginning of the most incredible adventure of all time…

BENEATH THE PLANET OF THE APES
By Michael Avallone
Thousands of years from now, in the buried ruins of what was once New York City, dark religious ceremonies pay tribute to the Great Bomb, bringer of life and death. In Ape City, the chimpanzees picket for peace while their gorilla leaders prepare for war. Two ruthless factions are racing towards calamity, as two men who somersaulted across time itself struggle for survival in a world that is no longer their own. 

ESCAPE FROM THE PLANET OF THE APES
By Jerry Pournelle
The time indicator races back through the years from 3955 to 1973. The spacecraft holds three survivors of a devastating cataclysm: Cornelius, his mate Zira, and Dr Milo. The world of 1973 welcomes the apes at first, pampering them for their unusual qualities. But when the truth of the thinking, speaking descendants that dominated Man and the Earth for centuries comes to light, this hospitality turns to threat.