How does John Keegan use imagery in The Mask of Command?

Examples of Imagery:

"What had prepared this extraordinary man for the mental, moral and physical ordeal of the four days of Waterloo - days at left those who had merely fought, without any of the strain of command, Wellington had borne and perhaps less of the danger, shocked into pallor and silence by the horrors of the slaughter, drugged by fatigue and physically deafened by the close range discharge of musketry?"
Part 2, Chap. 2, p. 103

"In the early light of a spring morning during the presidency of Abraham Lincoln, a small man on a large horse was galloping through the dense woodland beside the Tennessee River that went inland from the western shore."
Part 3, Chap. 1, p. 164