I read this book, it was written about over 2000 years ago in China, and it's still around in many Military Academies such as West Point.
In the 19th Century, Clausewitz tried to write a book that could surpass it's Chinese would be counterpart but he failed, the Clausewitz version defined mostly the ways Napoleon himself would fight his battles.
Even today, an over 2000 years old book written in China has never been surpassed, and is not only used on Military purposes but also in Politics and buiseness.
The first golden rule about this one is "Know your ennemy as well as you know yourself and even when fighting 1000 battles you'll never be defeated"
I really got inspired after reading it.