Carl Philipp Gottlieb von Clausewitz (IPA: [ˈklaʊzəvɪts]) (July 1, 1780 – November 16, 1831) was a Prussian soldier, military historian and influential military theorist. He is most famous for his military treatise Vom Kriege (complete German text available here), translated into English as On War (complete text available here).

Life and times
Vom Kriege (On War) is a long and intricate investigation of Clausewitz's observations based on his own experience in the Wars of the French Revolution and the Napoleonic Wars and on considerable historical research into those wars and others. It is shaped not only by purely military and political considerations but by Clausewitz's strong interests in art, science, and education.
Some of the key ideas discussed in On War include:
Clausewitz used a dialectical method to construct his argument, leading to frequent modern misinterpretation. As described by Christopher Bassford, professor of strategy at the National War College:
One of the main sources of confusion about Clausewitz's approach lies in his dialectical method of presentation. For example, Clausewitz's famous line that "War is merely a continuation of politics," ("Der Krieg ist eine bloße Fortsetzung der Politik mit anderen Mitteln") while accurate as far as it goes, was not intended as a statement of fact. It is the antithesis in a dialectical argument whose thesis is the point—made earlier in the analysis—that "war is nothing but a duel [or wrestling match, a better translation of the German Zweikampf] on a larger scale." His synthesis, which resolves the deficiencies of these two bold statements, says that war is neither "nothing but" an act of brute force nor "merely" a rational act of politics or policy. This synthesis lies in his "fascinating trinity" [wunderliche Dreifaltigkeit]: a dynamic, inherently unstable interaction of the forces of violent emotion, chance, and rational calculation.[1]
Another example of this confusion is the idea that Clausewitz was a proponent of total war as used in the Third Reich's propaganda in the 1940s. He did not coin the phrase as an ideological ideal--indeed, Clausewitz does not use the term "total war" at all. Rather, he discussed "absolute war" or "ideal war" as the purely logical result of the forces underlying a "pure," Platonic "ideal" of war. In what Clausewitz called a "logical fantasy," war cannot be waged in a limited way: the rules of competition will force participants to use all means at their disposal to achieve victory. But in the real world, such rigid logic is unrealistic and dangerous. As a practical matter, the military objectives in real war that support one's political objectives generally fall into two broad types: "war to achieve limited aims" and war to "disarm" the enemy--i.e., "to render [him] politically helpless or militarily impotent." Thus the complete defeat of one's enemies may be neither necessary, desirable, nor even possible.
In modern times the reconstruction and hermeneutics of Clausewitzian theory has been a matter of some dispute. between one of the most prominent was the analysis of Panagiotis Kondylis a Greek-German writer and philosopher who opposed the popular readings of Raymond Aron (in "Penser la Guerre, Clausewitz) and other liberal writers. In one of his most famous works which was titled Theory of War and first published in German -later translated in Greek by Kondylis himself. In this very influential book Kondylis opposes Raymond Aron's liberal perception of Clausewetzian theory. According to Raymond Aron in Penser La Guerre, Clausewitz, Clausewitz was one of the very first writers condemning the militarism of the military staff and their war-proness (based in the claim "war is a continuation of politics by other means") Kondylis claims that this a reconstruction that is not coherent with Clausewetzian thought. He claims that Clausewitz was morally indifferent to war and that his advices of political rule over war have nothing to do with pacifistic claims. For Clausewitz war is just a mean to the eternal quest for power of the reason d'etat in an anarchical and unsafe world. Other famous writers studying clausewitz's texts and have translated them in english are the war specialists Peter Parret (Princeton University) and Michael Howard and the philosopher, musician and game theorist Anatol Rapoport who has translated the Penguin edition and has comparatively studied Clausewitz and other theories of War such as Tolstoi...

the dialectical approach to military analysis
the methods of "critical analysis"
the nature of the balance-of-power mechanism
the relationship between political objectives and military objectives in war
the asymmetrical relationship between attack and defense
the nature of "military genius" (involving matters of personality and character, beyond intellect)
the "fascinating trinity" (wunderliche Dreifaltigkeit) of war
philosophical distinctions between "absolute" or "ideal war," and "real war"
in "real war," the distinctive poles of a) limited war and b) war to "render the enemy helpless"
"war" belongs fundamentally to the social realm—rather than to the realms of art or science
"strategy" belongs primarily to the realm of art
"tactics" belongs primarily to the realm of science
the importance of "moral forces" (more than simply "morale") as opposed to quantifiable physical elements
the "military virtues" of professional armies (which do not necessarily trump the rather different virtues of other kinds of fighting forces)
conversely, the very real effects of a superiority in numbers and "mass"
the essential unpredictability of war
the "fog" of war
"friction"
strategic and operational "centers of gravity"
the "culminating point of the offensive"
the "culminating point of victory" Influence
Clausewitz's Christian name is sometimes given in non-German sources as Carl Philipp Gottlieb, Carl Maria, or misspelled Karl due to reliance on mistaken source material, conflations with his wife's name, Marie, or mistaken assumptions about German orthography. Carl Philipp Gottfried appears on Clausewitz's tombstone and is thus most likely to be the correct version. The tombstone reads:
Hier ruht in Gott
Carl Philipp Gottfried von Clausewitz
koenigl. General-Major u. Inspecteur der Artillerie
geboren 1 Juni 1780
gestorben 16 Nov 1831
Which translates as:
Here rests with God
Carl Philipp Gottfried von Clausewitz
In the royal service, Major General and Inspector of the Artillery
Born 1 June 1780
Died 16 November 1831
There is no single "correct" spelling for German names before the early 19th century. Vital records were kept by pastors in their parish records. Different pastors used different spellings and commonly ignored how their predecessor may have spelled the same name. The name of the same individual can be found spelled differently in the same parish record, for example, if a pastor registered his birth and a different one his marriage and/or his death. It appears that pastors recorded names as they heard them and spelled them as they believed they should be spelled. Pastors treated persons of importance or high status such as nobility or civil or military officials more deferentially. For the names of such persons it can make sense to distinguish between such spellings as "Carl" or "Karl" even then. The situation changed radically in the Napoleonic era when French civil servants introduced greater discipline in keeping vital records in German lands. Spellings of family and given names were "frozen" in whatever state they happened to be in then. It was, however, not unusual for brothers who made their homes in different parishes to have their family names spelled differently. Such variations endure to this day and confound amateur genealogists who are not familiar with the fluidity of German spellings before the Napoleonic reforms. While spellings of names were fluid when Clausewitz was born, they had become firm by the time of his death. That is why it makes sense to accept the spelling of his name as recorded on his tombstone which, presumably, agrees with the vital records of his death.

Name
"War is politics by other means."

In the film Crimson Tide, the naval officers of the nuclear submarine have a discussion about the meaning of the quote "War is a continuation of politics by other means." The executive officer (played by Denzel Washington) contends that the captain (played by Gene Hackman) has taken a too simplistic reading of von Clausewitz.
In The Frosh Report, Anthony Frosh tells how he was concerned that his traveling companions would think negatively of him for expressing his "von Clausewitz attitude toward global conflict resolution." [2]
Sam Walker's non-fiction book Fantasyland references von Clausewitz, by name, briefly.
In Ian Fleming's "Moonraker", James Bond mentions that he has achieved Clausewitz's first principle in securing his base, though this base is a relationship for intelligence purposes and not a military installation.
In Steinbeck's East of Eden, Adam Trask's servant, Lee asks twice, "Did you ever read von Clausewitz?". Neither of the characters he asks has ever heard of Clausewitz. Lee responded the first time with, "Not very reassuring reading." This was Lee's way of expressing pessimism regarding the future outcome of the Great War.
In Lawrence of Arabia (1962), General Allenby (Jack Hawkins) contends to T.E. Lawrence (Peter O'Toole) that "I fight like Clausewitz, you fight like Saxe." (To which Lawrence replies, "We should do very well indeed, shouldn't we?")
In Sam Peckinpah's Cross of Iron (1977), Corporal Steiner (James Coburn)has an ironic conversation in the trenches between hostilities with the advancing Red Army with his comrade, Pvt. Schnurrbart, in which they refer to German philosophers and their views on war. Pvt. Schnurrbart: " ...and Von Clausewitz said, 'war is a continuation of politics with other means.'" "Yes," Steiner says, overlooking the trenches, " ...with other means."
He was mentioned in an episode of Popular by Nicole Julian. See also

Note regarding personal names: von is a title prefix denoting some sort of (former) nobility, translated as of. It is an inseparable part of the last name, not a first or middle name. Bibliography

Bassford, Christopher. Clausewitz in English: The Reception of Clausewitz in Britain and America, 1815-1945. New York: Oxford University Press, 1994. Full text on-line here.
Clausewitz, Carl Von (1976, rev.1984). On War, edited and translated by Michael Howard and Peter Paret., Princeton: Princeton University Press. ISBN 0-691-05657-9. 
Clausewitz, Carl von. Col. J. J. Graham, translator. Vom Kriege. On War — Volume 1, Project Gutenberg eBook.
Gerhard Muhm : German Tactics in the Italian Campaign , http://www.larchivio.org/xoom/gerhardmuhm2.htm
Gerhard Muhm, La tattica tedesca nella campagna d'Italia, in Linea gotica avamposto dei Balcani, a cura di Amedeo Montemaggi - Edizioni Civitas, Roma 1993
Paret, Peter. Clausewitz and the State: The Man, His Theories, and His Times. Princeton: Princeton University Press, 1976.
Rogers, Clifford J. "Clausewitz, Genius, and the Rules", The Journal of Military History, Vol. 66, No. 4. (2002), pp. 1167–1176.
Rothfels, Hans "Clausewitz" pages 93-113 from The Makers of Modern Strategy edited by Edward Mead Earle, Gordon A. Craig & Felix Gilbert, Princeton, N.J.: Princeton University Press, 1943.
Edward J. Villacres and Christopher Bassford, "Reclaiming the Clausewitzian Trinity," Parameters, Autumn 95, pp. 9-19, http://www.clausewitz.com/CWZHOME/Trinity/TRININTR.htm