He refused the post until continued to refuse the promotion legate of the Holy See, Cardinal Henry of Pisa, overrode his scruples. Having accepted it, his prophecy came true. From a worldling he became a devout Churchman, who took his duties seriously. This led to Henry's friendship turning to hatred.
In June 1170, Roger de Pont L'Évêque, the archbishop of York, along with Gilbert Foliot, the Bishop of London, and Josceline de Bohon, the Bishop of Salisbury, crowned the heir apparent, Henry the Young King, at York. This was a breach of Canterbury's privilege of coronation, and in November 1170 Becket excommunicated all three. While the three clergymen fled to the king in Normandy, Becket continued to excommunicate his opponents in the church, the news of which also reached Henry, who was in his French dominions.
Upon hearing reports of Becket's actions, Henry is said to have uttered words that were interpreted by his men as wishing Becket killed.The king's exact words are in doubt and several versions have been reported. The most commonly quoted, as handed down by oral tradition, is "Will no one rid me of this turbulent priest?"
Four of Henry's knights, Reginald FitzUrse, Hugh de Morville, William de Tracy and Richard le Breton, taking this as a royal command, wet to Canterbury and murdered Thomas.
Edward Grim, a monk of Canterbury, who was wounded in the attack, left an account:A short video from Catholic Online
The excommunication scene from the film 'Becket' (1964). Would that we till had excommunication by 'bell, book, and candle'!
Ad it' the fifth day of Christmas.