This book was real eye-opening for me. I heard about it when it was first released, but sort of dismissed it since on its face it seemed like just another pop alt-history, "you won't learn this in school" book. But it is well researched, and well regarded by historians[0].

[0] One example:https://www.tandfonline.com/doi/abs/10.1111/j.1931-0846.2006...