Fictional, that it. Whether for fantasy or historical fiction, I have an interesting resource for you.
Coup D’Etat: A Practical Handbook by Edward Luttwak – the title pretty much says it all. It uses historical examples to explain the preconditions needed for a coup to happen, the steps needed to plan and carry out a coup and what needs to occur in the aftermath to guarantee it’s a successful coup. He also uses historical examples of failed coups to show what went wrong and why.
Now, the word “coup d’etat” itself is fairly modern and this book was originally published in 1968 and uses examples from the early to mid 20th century. But history has had all kinds of quick, agressive operations that topple governments (“Et tu, Brutus”, anyone?). I see how the steps in this book can be adapted for use in less technical societies, like the one I’m creating for my WIP. I’m not too sure it would be all that helpful for anything set in the present or future because technology has changed so much. (Note: I was just creating the link to Amazon and noticed from the reviews that some people are using this book for reference in regard to fairly recent coup attempts, so maybe it’s not too dated after all!)
For someone like myself who has no experience with planning of military operations, this book has been a wealth of information.