"In the presence of English Barons, Henry II—who is now utterly vexed by Becket's actions—cries out: Will no one rid me of this troublesome priest? Believing the King meant for Becket to be murdered, four knights ride to Canterbury Cathedral and kill Becket on December 29, 1170."
https://www.awesomestories.com/asset/view/Murder-of-Thomas-Becket