Thomas Becket was the son of a London merchant who rose to become the closest friend and most powerful servant of King Henry II. As chancellor he lived in splendor, rode to war, and managed the king’s business brilliantly. In 1162 Henry made him Archbishop of Canterbury, the head of the church in England, expecting a loyal ally.

Instead Becket changed. He gave up his luxuries, wore a hair shirt under his robes, and began defending the church’s rights against the king, especially the right of churchmen accused of crimes to be tried in church courts instead of royal ones. The two old friends quarreled bitterly. Becket spent six years in exile in France, and when he came back in 1170 he immediately excommunicated bishops who had sided with the king.

Henry, in Normandy, flew into a rage when he heard. Exactly what he said is not known; the famous version, “Will no one rid me of this turbulent priest?”, was put into his mouth centuries later. But four of his knights took his words as a command. They crossed to England and on the evening of December 29, 1170, found Becket in Canterbury Cathedral, near the altar, as the monks were singing vespers. He refused to flee or to bar the doors of a church. They cut him down with their swords.

The killing horrified Europe. Miracles were soon reported at his tomb, and in 1173 the pope declared him a saint. The next year Henry himself walked barefoot into Canterbury and was whipped by the monks as penance. Becket’s shrine became the greatest pilgrimage site in England, until Henry VIII had it destroyed in 1538.

That is where English literature comes in. Two centuries after the murder, Geoffrey Chaucer imagined a group of pilgrims setting out from a London inn to visit “the holy blissful martyr,” and telling stories on the way. The Canterbury Tales would not exist without Becket’s shrine. Writers have kept returning to his story, most famously T. S. Eliot in his verse play Murder in the Cathedral (1935).