For the strategist - whether he's in business, the military, or any other competitive field of endeavor - here is the essence of the greatest military thinker in the world. Karl von Clausewitz (1780-1831) was a Prussian general and battlefield opponent of Napoleon (including on the retreat from Moscow). His book On War is the most famous and influential analysis of warfare and its principles ever written. As Colonel Harry G. Summers points out in his new foreword to this edition, it was the American military's failure to absorb Clausewitz's lessons that led to political and military catastrophe in Vietnam. This celebrated abridgement and translation by Colonel Edward M. Collins has since become a set military text and is credited by Colonel Summers with helping the American military achieve its smashing victory in the Persian Gulf. No student of war or strategy can ignore it, and no educated person's bookshelf can be without it.