By Dan Bilefsky

New York Times

LONDON >> On Dec. 29, 1170, four knights loyal to King Henry II crept up on the archbishop of Canterbury, Thomas Becket, in the city’s cathedral and murdered him with their swords after he clashed with the monarch.

More than eight centuries later, a bone fragment believed to be from Becket’s elbow traveled this week from Esztergom Basilica in Hungary, where it had been kept for centuries, back to England, where it will make several stops before returning to the site of his assassination.

Medieval scholars say the reasons for how and why the bone fragment wound up in Hungary are still a matter of debate. But at a time when Britain is contemplating whether to leave the European Union and Hungary is being accused of failing to uphold European values, the relic’s journey to England is being touted as a symbol of European unity.

It is also seen as a testament to reconciliation between the Roman Catholic Church and the Church of England.

“This is a chance for Hungary to show its European values,” said Naomi Howell, an associate research fellow in medieval studies at the University of Exeter in England. “It is also a symbol of the ongoing reconciliation of the Catholic Church and the Church of England, and the healing of the wounds still felt from the Protestant Reformation.”

Hampton Court Palace, where King Henry VIII broke off ties with the papacy in 1530 to divorce his first wife, held its first Roman Catholic service in more than 450 years in February. (He married his mistress, Anne Boleyn, whom he later beheaded.)

Becket had been a dear friend of King Henry II, with whom he played chess and hunted. But after he became archbishop of Canterbury, he resisted the monarch’s attempts to tame the church’s power. The knights, thinking the king wanted the archbishop dead, killed him.

Becket was canonized in 1173, and he became one of the most revered saints in England. His shrine in Canterbury Cathedral became a popular pilgrimage site, and it was immortalized in Geoffrey Chaucer’s “Canterbury Tales,” which followed the journey of a group of pilgrims to his tomb.

In medieval times, Becket’s bones were viewed as having mystical powers. According to legend, they could stop dogs from barking, and they cured a man who said he had suffered for 30 years from nocturnal attacks by a demon called the Incubus.

In another account of Becket’s prowess, a young girl who misplaced some cheese and who feared being beaten for the transgression prayed to Becket, who was said to have led her back to it, according to William MacLehose, a lecturer in the history of science and medicine at University College London.

The journey of the bone relic, which is held in a gold case, was celebrated Monday with a Holy Mass at Westminster Cathedral in London attended by President Janos Ader of Hungary and Cardinal Peter Erdo, archbishop of Esztergom-Budapest.

Along its journey, the elbow fragment will be temporarily reunited with a piece of Becket’s skull — normally kept at Stonyhurst College in northern England — before stopping at Rochester Cathedral on Friday and Canterbury Cathedral on Saturday. It will then return to Hungary.

Becket’s murder has long captured the popular imagination in Britain and around the world. T.S. Eliot depicted the archbishop’s assassination in a verse drama, “Murder in The Cathedral,” in 1935. In 1964, Richard Burton starred as the archbishop in the film “Becket,” alongside Peter O’Toole, who played King Henry II.

In Hungary, Becket was viewed as a potent emblem of resistance to state oppression in the communist era.

Mystery surrounds the question of how Becket’s remains ended up in Hungary. Howell said a leading theory is that the elbow fragment was taken to Hungary by Bishop Lukacs Banfi, who had studied with Becket in Paris and who was helped by Margaret of France, Henry II’s daughter-in-law.

In any case, its presence in Hungary helped protect it when the shrine containing part of Becket’s remains was destroyed during the Reformation in England, when the Catholic practice of revering saints was castigated.