In this role, he was not only the number one bishop out of a total of 108 bishops in the Anglican Church of England, he also led the worldwide Anglican Communion, which includes around 85 million people worldwide.
Now a successor must be found for him, or perhaps even a female successor. How will this work and what role will the King play?
It can be assumed that intensive discussions about possible candidates began immediately after the surprise resignation.
The selection process is in the hands of the Crown Nominations Commission, a committee consisting of 16 voting members. It will select one top candidate and a second who would also be suitable.
Archbishop of York also on election commission
The English Prime Minister Keir Starmer, an atheist by his own admission, will appoint the chairman of the commission, who must be a layperson. Ideally, it should be a person from public life with a positive commitment to the Church of England.
This electoral commission also includes the second most important bishop in the Church of England, Stephen Cottrell, the Archbishop of York. The other members are both clergy and laity - in contrast to the Catholic Church, where only clergy ultimately decide on the election of bishops in accordance with canon law. It is a central demand of the Catholic reform project Synodal Way that lay people should also be involved in the election of bishops in future.
The Commission must identify the challenges facing the Anglican Church in England and the world and select two candidates whom it believes are capable of meeting these challenges. The Crown Nominations Commission then forwards the names of its two candidates to the Prime Minister. The latter in turn informs King Charles III and advises him to appoint the top candidate.
The King is the temporal head of the Anglican Church. In earlier centuries, he could appoint, dismiss or even burn bishops at will, as he did in the 16th century. This happened in 1556 with Thomas Cranmer, the first Protestant Archbishop of Canterbury. Today, he has to accept the decision of the electoral committee and the Prime Minister.
According to her biographer Sarah Bradford, Queen Elizabeth II, who died in 2022, reacted very subtly to the election of a bishop she didn't really like. She then asked for more information, which the Prime Minister understood. If he nevertheless stuck to his proposals, she agreed in order to avoid an open conflict.
For King Charles III, this is the first Archbishop of Canterbury in whose selection he has been officially involved. Once he has given his consent, the top candidate is informed and asked whether he or even she wishes to accept the election. The Prime Minister then announces the name and the College of Clergy at Canterbury Cathedral formally elects him or her as the new Archbishop.
Three promising candidates
A further committee of bishops must also give its approval before the candidate is formally installed in office in the cathedral. In contrast to the Catholic Church, which has a precise timetable for electing a successor to the Pope so that the most important office in the Church does not remain vacant for long, the Anglican election can drag on.
According to initial media reports, the chances are good for these three bishops: Martyn Snow, the Bishop of Leicester, Graham Usher, the Bishop of Norwich and Guli Francis-Dehqani, the Bishop of Chelmsford. If Francis-Dehqani is elected, she would be the first woman to hold this office. She also has an unusual CV. She only came to the UK from Iran after the revolution at the age of 13.
Whoever gets the top job in the Anglican Church, he or she must somehow hold the fractured community together. Conservatives and progressives have their strong camps and the question of how to deal with homosexual partnerships still has the potential to cause a rift.