I have been trying to recall the title of a book I read about 25 years ago (1987), I have tried to find it again a couple of times over the years without any luck.
The story takes place on earth, which has been invaded and conquered by aliens. The humans have become servants or slaves. One of the primary human characters is the human servant of an alien leader.
If I remember correctly, the aliens are much bigger than humans, I keep thinking of horses or elephants for some reason with regard to the aliens. At the end, somehow the human slaves have forced the aliens to abandon their conquest of earth, but I don't remember exactly why.
I think it was something to do with simply refusing to be obedient, which the aliens could not comprehend, but I'm not sure about that. I think the book ends with the alien leader (and the rest of the aliens) blasting off from earth in a rocket.
Does anyone recognize what book I'm referring to?
Thanks for any help!