Alexander III
Rolando Bandinelli · 1159 – 1181
Battled Emperor Frederick Barbarossa for nearly two decades and convened the Third Lateran Council, which established rules for papal elections.
Rolando Bandinelli was a renowned canon lawyer from Siena who became pope in 1159. His pontificate was consumed by conflict with Emperor Frederick Barbarossa, who supported a series of antipopes. Alexander spent years in exile in France but eventually prevailed. At the Third Lateran Council in 1179, he established that a two-thirds majority of cardinals was required for papal election — a rule that shaped conclaves for centuries. He also canonized Thomas Becket.
Why He Matters
Alexander III's rule that popes must be elected by a two-thirds supermajority of cardinals was one of the most consequential decisions in Church governance. It prevented narrow factions from seizing the papacy and remains the basic framework for conclaves today.