On 29 December 1170, Thomas Becket was killed inside Canterbury Cathedral.

The murder was carried out by four knights, but it grew out of a longer conflict between Becket and Henry II. Becket was not a distant critic of the king. He had been Henry’s chancellor, a close royal servant and a man trusted with the work of government. When Henry made him archbishop of Canterbury in 1162, he seems to have expected support in bringing the English Church more firmly under royal authority.

That expectation failed.

As archbishop, Becket resisted the king over the Church’s rights and privileges. The dispute was about power: who had authority over clergy, how church courts should work and how far royal law could reach into church life. These were serious questions in a medieval kingdom. Henry wanted order and royal control. Becket defended the Church’s independence and status. Their personal quarrel became a public test of authority.

The conflict became bitter enough to drive Becket into exile for several years. He returned to England in 1170, but the reconciliation did not last. Becket remained defiant, and Henry’s anger towards him became part of the story. The famous line about being rid of a troublesome priest is too uncertain to treat as a safe quotation. The safer point is the effect. Four knights understood the king’s anger as a reason to act.

They went to Canterbury and confronted Becket in the cathedral. There, in one of the most sacred spaces in England, they killed the archbishop.

The setting changed the meaning of the crime. This was more than the removal of a political opponent. It was violence against the Church, carried out at the altar of English religious life. Becket’s death gave his side a force it had not had while he was alive. The king’s problem did not end with the murder. It became worse.

Reports of miracles soon gathered around Becket’s tomb. Canterbury became a major place of pilgrimage. In 1173, Becket was canonised as a saint. Henry, who had once expected obedience from his archbishop, was forced into public penance at Canterbury in 1174.

That reversal gives the date its weight. Henry II remained king, and royal power did not collapse. But the murder showed that royal anger could outrun royal control. Becket had challenged Henry in life. In death, he became harder to answer.