Carl Philipp Gottfried von Clausewitz was born in the 18th century in Prussia. A contemporary to Napoleon, Clausewitz spent his life in the military, advancing through the ranks to become Major General. Later on in his life he served as a military theorist and the director of the Prussian Military Academy.
Clauzewitz's most important work, his magnum opus, is titled "On War". An unfinished work (Clausewitz considered only the first of eight books truly finished), "On War" was published posthumously by his wife.
Clausewitz speaks on warfare with clarity and from many perspectives: he looks at war as a duel of violent forces on an extensive scale, a game of probabilities and chance, and also as a tool of state.
He describes which attributes a general, a common soldier, and the army as a whole should have.
Clausewitz concludes that war is never an isolated act and that a positive theory (a system) on the art of war is impossible.
An able general should be a genius who raises himself above the rules, a person of strong presence of mind, who is capable of simplifying and integrating the multitude of information and probabilities.
As Clausewitz writes, "science must become art".
There are two major deficiencies to the philosophy of Clausewitz in "On War":
Firstly, he considers only a war between states (by the use of their armies) to be an act of warfare.
The second is more interesting. As a general strategy, Clausewitz advocates superiority of numbers. He says, "The best strategy is always to be very strong, first generally then at the decisive point."
This proposition makes for an interesting analysis of western military thought and western military history.
"On War" by Clausewitz had wide influence on western militaries; it is considered to be a cornerstone of western military philosophies, comparable only to Sun Tzu's "Art Of War" by significance.