The Origins of Military Thought: From the Enlightenment to Clausewitz (Oxford Historical Monographs) Paperback – 5 September 1991

Eye opening! I had suspected some of this, was largely ignorant about the other military Enlightenment thinkers, and enjoyed the thorough background from the two schools of thought- Enlightenment into the German Romantic traditions.

CAVEAT: The description of this book is highly deficient. It doesn't mention that this book is just the first third of Azar Gat's book "History of Military Thought". You're far better off with the History of Military Thought.