They are the unforgettable leaders who inspired their troops, the tacticians who devised the wiliest strategies, the military mavericks who won the wars. Although more than 2000 years separate Alexander the Great from Giap, the single-minded commander of the North Vietnamese forces that defeated the U.S., each of these outstanding characters has something to teach us about military history. They include Shaka Zulu, Stonewall Jackson, Garibaldi, Lawrence of Arabia, and Patton--12 in all.