The Conquest of the Illinois, also known as "Clark's Memoir", is one of the most noteworthy of the books on American history: it's a first-hand account by the chief participant, and thus a key primary source for the early history of the United States.
You know how in Star Wars, there are all these aliens, and none of them are speaking the same language, and they all look totally different and come from different cultures, but everybody is totally chill about it and takes it in stride and comes up with helpful ways of understanding cultural difference like "Wookies are known to take people's arms outta their sockets when they lose" and in fact everyone seems to understand what everyone else is saying all the time, even though none of them are speaking the same language so HOW IS THAT EVEN POSSIBLE, and sometimes people adopt other people's customs as a way of making an impression on those people, but other times they scorn other people's customs as a way of making an impression on those people, but either way people are manipulating each other culturally all the time, and in general everyone always has this heightened awareness of cultural "code" that they kind of take for granted but which they are constantly subtly deploying while they strategize about their epic military quests?
This book has taught me that, in the past, Illinois was a lot like Star Wars.