Jacques-Antoine-Hippolyte, comte de Guibert (1743-1790) dedicated his life and career to creating a new doctrine for the French army. Little about this doctrine was revolutionary. Indeed, Guibert openly decried the anarchy of popular participation in government and looked askance at the early days of the Revolution. Rather, Guibert’s doctrine marked the culmination of an evolutionary process that commenced decades before his time and reached fruition in the Réglement of 1791, which remained in force until the 1830s. Not content with military reform, Guibert demanded a political and social constitution to match. His reforms required these changes, demanding a disciplined, service-oriented society and a functional, rational government to assist his reformed military. He delved deeply, like no other contemporary writer, into the linkages between society, politics, and the military throughout his career and his writings. Guibert exerted an overwhelming influence on military thought across Europe for the next fifty years. His military theories provided the foundation for military reform during the twilight of the Old Regime. The Revolution, which adopted most of Guibert’s doctrine in 1791, continued his work. A new army and way of war based on Guibert’s reforms emerged to defeat France’s major enemies. In Napoleon’s hands, Guibert’s army all but conquered Europe by 1807. As other nations adopted French methods, Guibert’s influence spread across the Continent, reigning supreme until the 1830s. This dissertation adopts a biographical approach to examine Guibert’s life and influence on the creation of the French military system that led to Napoleon’s conquest of Europe. As no such biography exists in Anglophone literature, such a work will fill a crucial gap in understanding French military success to 1807. It examines the period of French military reform from 1760 to the creation and use of Napoleon’s Grande Armée from 1803 to 1807, illustrating the importance of Guibert’s systemic doctrine in the period. Moreover, the work argues that Guibert belongs in the ranks of authors whose works exerted a primary influence on the French Enlightenment and Revolution by establishing Guibert as a “Great Man” of the Republic of Letters between 1770 and his death in 1790.