In January of 1208, a papal legate was murdered on the banks of the Rhone in southern France. A furious Pope Innocent III accused heretics of the crime and called upon all Christians to exterminate heresy between the Garonne and Rhone rivers--a vast region now known as Languedoc--in a great crusade. This most holy war, the first in which Christians were promised salvation for killing other Christians, lasted twenty bloody years--it was a long savage...