9. The Army on the March
"High and sharp," or rising to a peak, is of course somewhat exaggerated as applied to dust. The commentators explain the phenomenon by saying that horses and chariots, being heavier than men, raise more dust, and also follow one another in the same wheel-track, whereas foot-soldiers would be marching in ranks, many abreast. According to Chang Yu, "every army on the march must have scouts some way in advance, who on sighting dust raised by the enemy, will gallop back and report it to the commander-in-chief." Cf. Gen. Baden-Powell: "As you move along, say, in a hostile country, your eyes should be looking afar for the enemy or any signs of him: figures, dust rising, birds getting up, glitter of arms, etc."[1="Aids to Scouting," p. 26.]
Chang Yu says: "In apportioning the defenses for a cantonment, light horse will be sent out to survey the position and ascertain the weak and strong points all along its circumference. Hence the small quantity of dust and its motion."