For one of the most famous battles of the Era:

The Battle, by Alessandro Barbero

The book is not an easy read, but it shows the circumstance of the battle. English Empire fans take note: the author wasn't too kind on the notion of "English supremacy" in the battle, nor on Sir Wellington. While Napoleon did make several mistakes that day, the book also shows why he made some of these mistakes. The book only focus on the days of the battle, not the entire Napoleonic Wars.

Annie