During the War of the First Coalition, the Army of the Sambre and Meuse, commanded by Jean-Baptiste Jourdan, played the decisive role against Coalition forces in the Low Countries. Created in June 1794, the army defeated the Allies at the battle of Second Fleurus on 26 June 1794 and commenced the Coalition’s retreat to the Rhine River. At the end of the year, Jourdan led the army to winter quarters along the left bank of the Rhine and achieved France’s historically momentous “natural frontier.” Despite its historical significance, the Army of the Sambre and Meuse has suffered from scant historical attention. Based largely on archival research, this thesis provides a detailed examination of the army’s performance during the Fleurus campaign. In addition, this thesis pursues several broader themes. A detailed study of the Sambre and Meuse Army provides insight into institutional military change during the late eighteenth century. While historians traditionally argue that the French Revolution inaugurated an attendant “revolution in military affairs,” this thesis presents evidence of evolutionary changes and continuities. Another important theme is the question of the combat effectiveness of French field armies during the Revolutionary epoch. Although historians typically present the French armies as unique and superior to their Old Regime opponents, this thesis demonstrates the effective parity between the armies of Revolutionary France and the Old Regime on the battlefield.

After conquering Belgium and the Rhineland in 1794, the French Army of the Sambre and Meuse faced severe logistical, disciplinary, and morale problems that signaled the erosion of its capabilities. The army’s degeneration resulted from a revolution in French foreign policy designed to conquer the natural frontiers, a policy often falsely portrayed as a diplomatic tradition of the French monarchy. In fact, the natural frontiers policy – expansion to the Rhine, the Pyrenees, and the Alps – emerged only after the start of the War of the First Coalition in 1792. Moreover, the pursuit of natural frontiers caused more controversy than previously understood. No less a figure than Lazare Carnot – the Organizer of Victory – viewed French expansion to the Rhine as impractical and likely to perpetuate war. While the war of conquest provided the French state with the resources to survive, it entailed numerous unforeseen consequences. Most notably, the Revolutionary armies became isolated from the nation and displayed more loyalty to their commanders than to the civilian authorities. In 1797, the Sambre and Meuse Army became a political tool of General Lazare Hoche, who sought control over the Rhineland by supporting the creation of a Cisrhenan Republic. Ultimately, troops from Hoche’s army removed Carnot from the French Directory in the coup d’état of 18 fructidor, a crucial benchmark in the militarization of French politics two years before Napoleon Bonaparte’s seizure of power. Accordingly, the conquest of the Rhine frontier contributed to the erosion of democratic governance in Revolutionary France.