In the 14th and 15th centuries, while Japan's samurai fought high-profile battles in the open, stealthy ninjas fought in the shadows. Serving variously as mercenaries, spies, and guards, the highly trained, secretive warriors carried out guerilla operations under the cover of darkness at the service of warlords. This title for readers age 12 and up surveys the history of the ultra-quiet martial arts masters. It covers key fighters, weapons, combat skills, and rules of warfare. Includes a glossary, sidebars, index, and further resources.