born March 6, 1779, Payerne, Switz. died March 24, 1869, Passey, France Swiss-French general and military theorist. After a volunteer stint with the French army (1798-1800), he wrote his Treatise on Grand Military Operations, 5 vol. (1805). He was appointed staff colonel in 1805 by Napoleon I, who had read his book. He was created a baron after the Treaties of Tilsit (1807). He rose to the post of chief of staff, but unjust treatment by his superiors prompted him to resign (1813), and thereafter he fought for France's enemy, Russia. Of his numerous later works on military history and strategy, the best known are Principles of Strategy (1818) and Summary of the Art of War (1838). He was the first to fix divisions between strategy, tactics, and logistics, and his systematic attempt to define the principles of warfare made him a founder of modern military thought