"Carl Philipp Gottfried (or Gottlieb) von Clausewitz, 1 June 1780 – 16 November 1831, was a Prussian general and military theorist who stressed the "moral" (meaning, in modern terms, psychological) and political aspects of war. His most notable work, Vom Kriege (On War), was unfinished at his death. Clausewitz was a realist in many different senses and, while in some respects a romantic, also drew heavily on the rationalist ideas of the European Enlightenment.
Carl von Clauswitz was the son of a a middle-class family. His father had been a professor of theology, his father had been a lieutenant in the Prussian army. Calauzwitz entered the Prussian military service at the age of twelve as a Lance-Corporal. At age 26 he with 25,000 others including Karl Wilhelm Ferdinand, Duke of Brunswick, were taken as prisoners after being defeated by Napoleon and held in France from 1807 to 1808.
He returned to Prussia where he married Countess Marie von Brühl on 10 Dec. 1810.
In the following years he continued to be in the military including time serving in the Russian Army. Clausewitz was promoted to Major-General in 1818 and appointed director of the Kriegsakademie, where he served until 1830. During this period he began work on On War but did not complete the work. In 1830 he returned to duty with the army.
His widow edited, published, and wrote the introduction to the philosophy of war in 1832. She wrote the preface for On War and by 1835 had published most of his collected works. She died in January 1835.
His influence on military thought can not be underestimated. Everyone seems to know his name, unfortunately not everyone has spent the time to read his work. There are multiple translations available in English.
Carl von Clausewitz continues to be a important to military thought, as shown by this opening paragraph of Clausewitz and his Works by Christopher Bassford:
"Since the close of the Vietnam War, the ideas expounded by the Prussian military theorist Carl von Clausewitz (1780-1831) have come—very often in twisted, garbled, or mutated form—to thoroughly permeate American military writing (doctrinal, theoretical, and historical). His book On War (published posthumously in Prussia as Vom Kriege in 1832), was adopted as a key text at the Naval War College in 1976, the Air War College in 1978, and the Army War College in 1981. It has always been central at the U.S. Army's School for Advanced Military Studies at Leavenworth (founded in 1983). The U.S. Marine Corps's brilliant little philosophical field manual FMFM 1: Warfighting (1989) was essentially a distillation of On War (with a heavy maneuverist flavoring from Sun Tzu), and the more recent Marine Corps Doctrinal Publications (MCDPs, c.1997) equally reflect many of Clausewitz's basic concepts.
"Deutschland Tote und Beerdigungen, 1582-1958," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:JWP7-Y4S : 28 November 2014), Clausewitz in entry for Von H?Ulsen Clausewitz, ; citing p 10, reference p 10; FHL microfilm 70,704.