How does E. B. Sledge use imagery in With the Old Breed, at Peleliu and Okinawa?

From the text:

"On the chilly January morning of our first lesson in mortars, we sat on the deck under a bright sky and listened attentively to our instructor.
"'The 60mm mortar is a smoothbore, muzzle-loaded, high-angle-fire weapon. The assembled gun weighs approximately forty-five pounds and consists of the tube—or barrel—bipod, and base plate. Two or sometimes three 60mm mortars are in each rifle company. Mortars have a high angle of fire and are particularly effective against enemy troops taking cover in defilades or behind ridges where they are protected from our artillery. The Japs have mortars and know how to use 'em, too. They will be particularly anxious to knock out our mortars and machine guns because of the damage these weapons can inflict on their troops.'" p. 19