A discussion of the elements that made the Armée du Nord victorious on the battlefield ought to proceed from an informed understanding of combat effectiveness. Far too many histories are founded upon simplistic or vague assumptions concerning troop performance under fire. Rarely do authors even bother to elaborate the underpinnings of their analyses. Distortion and confusion can result from such methodological carelessness. To avoid these pitfalls, this study begins with an attempt to identify the factors that determine the quality of performance in combat and to define the relationships among them.