U.S. Department of the Army 
U.S. Army Guide to Map Reading and Navigation [EPUB ebook] 

It requires no prior knowledge of these subjects. Sections include map care, comprehension of map symbols, military symbols, grid reference systems, and interpretation of aerial photographs. After the basics are covered, the second half moves to land navigation varying terrains, elevations, day-night variations. Map and compass work is thoroughly explained. Finally, extreme scenarios desert, mountain, jungle, arctic, and urban terrains are all explored.