December 1, 1170: Banished earlier by king Henry II because he sided with the church against the crown, archbishop of Canterbury Thomas a Becket returns, electrifying all of England. Henry orders his former friend's execution, and Becket is slain by four knights while at vespers December 29. (T.S. Eliot's play Murder in the Cathedral is a fascinating exploration of the event.)

December 1, 1521: Pope Leo X, enemy of Martin Luther (whom he excommunicated in 1520), dies. Though sincere in his faith ...