On December 29, 1170 the Thomas Becket, the  Archbishop of Canterbury, was murdered in the Canterbury Cathedral. 

“Where is Thomas Becket, traitor to the king and the kingdom?” the knights then rushed at him… roughly manhandling and dragging him, intending to kill him outside the church, or carry him away in chains. 
The Lives of Thomas Becket, ed. and trans. by Michael Staunton (Manchester: Manchester University Press, 2001), p. 201.

Thomas Becket’s assassination (1170)
Part of the History of the British Isles (II) series
Issued by Tristan da Cunha in 2010
Designed by CASCO Services

Becket returned from exile on 1 December 1170. Contemporary reports record that he was greeted on his journey back to the Cathedral by cheering crowds and rejoicing monks, but he faced increasing hostility by the authorities loyal to the king. Meanwhile, the Archbishop of York and the Bishops of London and Salisbury, furious that they had been excommunicated, travelled to Henry’s royal court in Normandy where they relayed Becket’s actions to the king. Henry was outraged and, although it is unclear whether he ever specifically ordered retribution for Becket’s actions, his furious outburst prompted four knights – Reginald FitzUrse, William de Tracy, Hugh de Morville and Richard le Bret – to travel to Canterbury in search of Becket.  
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As Grim recounts, Becket held tight onto one of the Cathedral’s pillars to prevent them seizing him, and it was at this point that one of the knights raised his sword for the first time, bringing it down on Becket, slicing off the crown of his head. Two of the other knights then started to attack Becket and most of the monks fled. The third blow brought the Archbishop’s life to an end. 
Thomas Becket: the murder that shook the Middle Ages | British Museum