A manuscript that had been asleep for nearly a century in the family archives, was found by Eglise Neuve Issac (Dordogne) The author is Peter Lancesseur, born in 1874, enlisted in 1893, a cadet at St. Maixent in 1900, lieutenant in 1906, captain at the beginning of the Great War, he finished as a battalion commander, having received the Legion of Honor and the Croix de Guerre with Palm, having retired with the rank of lieutenant-colonel in 1926, flowing quiet days in Périgord until his death in 1962. He had written The enigma of Waterloo during his time in the special reserves from 1912 to 1914. The text has remained unpublished until now. How English stuck and was unable to maneuver, aided by the Prussians being extremely unprepared, they could beat him at Waterloo, where his strategic genius has never been more active? Although many factors have played against him: the rain that soaked the ground, the lack of enthusiasm of senior officers and generals, faults characterized by some bad luck, ... And yet, says Lieutenant-Colonel Lancesseur, defeat remains an enigma. In the early 20th century, all France military dreamed of revenge on Germany Prussia. Napoleon is irreplaceable reference. If Lancesseur evokes the great battle finally lost, it is to show that its tragic outcome was unlikely that a slip in a campaign that is in honor of our military and its illustrious chief. The narrative heavily documented, repeating events hour by hour, and sometimes minute by minute, takes the reader through panting.