British Catholics were in a state of confusion and amazement today after the Vatican confirmed the Pope was resigning due to health reasons.
Pope Benedict, who made the announcement in Latin, will step down on February 28th.
"After having repeatedly examined my conscience before God, I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry," he said.
"However, in today’s world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith,both strength of mind and body are necessary, strength which in the last few months, has deteriorated in me to the extent that I have had to recognise my incapacity to adequately fulfill the ministry entrusted to me.
"Dear brothers, I thank you most sincerely for all the love and work with which you have supported me in my ministry and I ask pardon for all my defects."
The Vatican said the period of vacant Papacy will be "as brief as possible".
David Cameron said: "I send my best wishes to Pope Benedict following his announcement today. He has worked tirelessly to strengthen Britain's relations with the Holy See.
"His visit to Britain in 2010 is remembered with great respect and affection. He will be missed as a spiritual leader to millions."
Ed Miliband commented: "His decision to stand down is a brave one and we know he won’t have reached it lightly."
"The choice of a successor is clearly an important one for the Catholic Church. Our thoughts are with those who must make such a critical decision on behalf of millions around the world."
Bookmakers Ladbrokes made Peter Turkson from Ghana the 5/2 favourite to win the Papal election.
Minutes after the announcement, the Vatican website crashed under the weight of traffic.
Pope Benedict is the first Pope to resign since Gregory XII in 1415, who was trying to end the Western Schism, in which three people claimed the Papal throne.
Before that the last Pope to resign was Celestine V in 1294.
There has been speculation about the 85-year-old's health since last year, when he often appeared exhausted and sullen.
He admitted at a Morning Mass in April to being on "the final leg of the path of my life", but speculation was dampened by the fact very few observers were even aware Popes could resign.
Despite being criticised for quitting as an MP last year, former Tory backbencher Louise Mensch took to Twiter to atttack the Pope's decision.
"The Holy Father was one of the Church's best theologians. It is stunning, dreadful that he would 'retire'," she wrote.
"The only valid reason I can think of would be if he some degenerative disease of the mind. I hope that is not the reason.
"John Paul II taught from his deathbed exhorting crowds to prayer as they chanted in St. Peter's Square. Til the end he was Pope."
Mohammed Shafiq, chief executive of the Ramadhan Foundation, said the Pope never really recovered from his early attack on Islam.
"His Papacy will be sadly remembered from the Muslim world by his distortion and attack on Islam as he came to the Papacy," he said.
"This sadly meant the hard work of his predecessor Pope John Paul II was tarnished and required extensive work to rebuild ties between Christianity and Islam."
He added: "Faith in the world is under attack from rampant secularism and it requires people of all faith to come together, Muslims, Jews, Christians, Hindus, Sikhs and those of all faith need to ensure that faith is not trashed as we so often see."
Pope Benedict has been a controversial figure as Pope. The German, who was involved in the Hitler Youth as a child, took a hardline position on issues such as contraception and was unable to move on from the deadly reputational damage of the child sex scandals hitting the Catholic Church.
He was granted the rare honour of addressing both house of parliament during an official visit in 2010, although some were offended by his warning that the UK was falling victim to "atheist extremism".
Pope statement in full
I have convoked you to this Consistory, not only for the three canonizations, but also to communicate to you a decision of great importance for the life of the Church. After having repeatedly examined my conscience before God, I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry. I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only with words and deeds, but no less with prayer and suffering. However, in today’s world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith, in order to govern the bark of Saint Peter and proclaim the Gospel, both strength of mind and body are necessary, strength which in the last few months, has deteriorated in me to the extent that I have had to recognize my incapacity to adequately fulfill the ministry entrusted to me. For this reason, and well aware of the seriousness of this act, with full freedom I declare that I renounce the ministry of Bishop of Rome, Successor of Saint Peter, entrusted to me by the Cardinals on 19 April 2005, in such a way, that as from 28 February 2013, at 20:00 hours, the See of Rome, the See of Saint Peter, will be vacant and a Conclave to elect the new Supreme Pontiff will have to be convoked by those whose competence it is.
Dear Brothers, I thank you most sincerely for all the love and work with which you have supported me in my ministry and I ask pardon for all my defects. And now, let us entrust the Holy Church to the care of Our Supreme Pastor, Our Lord Jesus Christ, and implore his holy Mother Mary, so that she may assist the Cardinal Fathers with her maternal solicitude, in electing a new Supreme Pontiff. With regard to myself, I wish to also devotedly serve the Holy Church of God in the future through a life dedicated to prayer.
From the Vatican, 10 February 2013
BENEDICTUS PP XVI