Books that have a highly intelligent tactican/diplomat main character and their thought processes

Hello! I'm a big fan of media in which the main character is intelligent in a way you can actually see the thought process of. I finished reading There Is No Anti-Memetics Division and while they may not have been geniuses, the thought processes of these characters who are somewhat intelligent was fascinating to watch. But the thought process there was related to SCPs and other matters rather than battle/diplomacy.

The best example of this is this online series on Reddit (that is oh so sadly discontinued) called the Demon's accountant which is about a guy using his wits to win fights/wars that he should not have been able to win.