 It was unfinished when Clausewitz died and contains material written at different stages in his intellectual evolution, producing some significant contradictions between different sections.The sequence and precise character of that evolution is a source of much debate, as are exact meaning behind his seemingly contradictory claims (discussions pertinent to the tactical, operational and strategic levels of war are one example).Clausewitz constantly sought to revise the text, particularly between 1827 and his departure on his last field assignments, to include more material on "people's war" and forms of war other than high-intensity warfare between states, but relatively little of this material was included in the book.