Ten men, battalions, or divisions, fighting fifteen men, battalions, or divisions, conquer⁠—that is, kill or take captive⁠—all the others, while themselves losing four, so that on the one side four and on the other fifteen were lost. Consequently the four were equal to the fifteen, and therefore 4x = 15y. Consequently x/y = 15/4. This equation does not give us the value of the unknown factor but gives us a ratio between two unknowns. And by bringing variously selected historic units (battles, campaigns, periods of war) into such equations, a series of numbers could be obtained in which certain laws should exist and might be discovered.

The tactical rule that an army should act in masses when attacking, and in smaller groups in retreat, unconsciously confirms the truth that the strength of an army depends on its spirit. To lead men forward under fire more discipline (obtainable only by movement in masses) is needed than is needed to resist attacks. But this rule which leaves out of account the spirit of the army continually proves incorrect and is in particularly striking contrast to the facts when some strong rise or fall in the spirit of the troops occurs, as in all national wars.