Momentum (quantity of motion) is the product of mass and velocity.

In military affairs the strength of an army is the product of its mass and some unknown x .

Military science, seeing in history innumerable instances of the fact that the size of any army does not coincide with its strength and that small detachments defeat larger ones, obscurely admits the existence of this unknown factor and tries to discover it⁠—now in a geometric formation, now in the equipment employed, now, and most usually, in the genius of the commanders. But the assignment of these various meanings to the factor does not yield results which accord with the historic facts.

Yet it is only necessary to abandon the false view (adopted to gratify the “heroes”) of the efficacy of the directions issued in wartime by commanders, in order to find this unknown quantity.