The Battle is a book Balzac always wanted to write, mentioning it in his correspondence to friends, but never actually getting beyond the research stage during his lifetime. Balzac wanted to explore how a man such as Napoleon reacted in the heat of battle, and to plunge the reader into the horror and fascination of the battlefield.
The only surviving line is "On Tuesday 16th May 1809 ... ' and Patrick Rambaud uses this beginning to write the book Balzac might have written. It is the account of the battle of Essling, near Vienna which history has now judged to be Napoleon's first major defeat on land in Europe. Forty thousand men died in forty-eight hours, and Rambaud leaves no detail unexamined in this work of historical fiction.