9. The Army on the March
These are the four useful branches of military knowledge
Those, namely, concerned with (1) mountains, (2) rivers, (3) marshes, and (4) plains. Compare Napoleon's "Military Maxims," no. 1.
which enabled the Yellow Emperor to vanquish four several sovereigns.
Regarding the "Yellow Emperor": Mei Yao-ch`en asks, with some plausibility, whether there is an error in the text as nothing is known of Huang Ti having conquered four other Emperors. The SHIH CHI (ch. 1 ad init.) speaks only of his victories over Yen Ti and Ch`ih Yu. In the LIU T`AO it is mentioned that he "fought seventy battles and pacified the Empire." Ts`ao Kung's explanation is, that the Yellow Emperor was the first to institute the feudal system of vassals princes, each of whom (to the number of four) originally bore the title of Emperor. Li Ch`uan tells us that the art of war originated under Huang Ti, who received it from his Minister Feng Hou.