'Invisible Armies' by Max Boot

From the publisher: Beginning with the first insurgencies in the ancient world — when Alexander the Great discovered that fleet nomads were harder to defeat than massive conventional armies — Max Boot, best-selling author and military advisor in Iraq and Afghanistan, masterfully guides us from the Jewish rebellion against the Roman Empire up through the horrors of the French-Indochina War and the shadowy, post-9/11 battlefields of today.