I want to write a book about historical figures. Do I violate copyright when I do so?
By writing a historical book you do not violate any forms of copyright as far as I am aware, many people have written books using historical figures and I cannot name one person who has been taken to court because of this. However, it also depends on how you write the historical figure. If you write them in a way that could or is supposed to offend someone then you could get into a lot of trouble regarding the media and your book would likely not be accepted by publishers.
But I STRONGLY suggest studying writing and history first before ever attempting to write a book like this, or even a book at all for that matter. Usually when writing a historical book you only attract certain types of people and they will be very fussy over the details of how you wrote these figures and even if you got facts right. So please do some research before doing anything out of your capability.
This is the best answer of mine I could give you but I hope it has helped.