In 1105, six years after the first crusaders from Europe conquered Jerusalem, a Damascene Muslim jurisprudent named 'Ali ibn Tahir al-Sulami (d. 1106) publicly dictated an extended call to the military jihad (holy war) against the European invaders. Entitled Kitab al-Jihad (The Book of the Jihad), al-Sulami's work both summoned his Muslim brethren to the jihad and instructed them in the manner in which it ought to be conducted, covering topics as diverse as who should fight and be fought, treatment of prisoners and plunder, and the need for participants to fight their own inner sinfulness...