Canonized in 1297 as Saint Louis, King Louis IX of France (r. 1226-1270) was one of the most important kings of medieval history and also one of the foremost saints of the later Middle Ages. As a saint, Louis became the centerpiece of an ideological program that buttressed the ongoing political consolidation of France and underscored Capetian claims of sacred kingship. M. Cecilia Gaposchkin reconstructs and analyzes the process that led to...