Pope Benedict XVI, Supreme Pontiff of the Roman Catholic Church, is stepping down at the end of this month due to age and infirmity.

It is the first resignation of a sitting pope in 600 years. Not since an agreement to heal a schism that arose due to competing papal claimants, forcing Gregory XII out of office in 1415, has there been a papal resignation.

Vatican watchers -- the Italian press, which usually has excellent inside info on the papacy - was blindsided by the announcement. Not even the pope's closest aides were privy to his decision.

Benedict - the former Cardinal Ratzinger - was always seen as a caretaker pope. Elected in 2005 at the age of 78 following the death of his predecessor John Paul II, Ratzinger was considered  a placeholder for other candidates who were in their 50's at the time and considered too young to fill the office.

In the last years of John Paul's pontificate, Ratzinger headed up the powerful and influential office of Prefect for the Doctrine of Faith. He was able to place key allies in positions of power so that when the conclave met following the death of John Paul. his election was relatively smooth. It took only three days for the College of Cardinals to decide.

His statement on his resignation sets a precedent that may overturn 1800 years of church tradition that kept the pope at his post until his death.

In a statement, the pope said in order to govern "...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."

Before he was elected Pope, the former Cardinal Joseph Ratzinger was known by such critical epithets as "God's rottweiler" because of his stern stand on theological issues.

But after several years into his new job he showed that he not only did not bite but barely even barked.

In recent months, the Pope has looked increasingly frail in public sometimes being helped to walk by those around him.

A Vatican spokesman said the pontiff would step down from 2 p.m. ET on February 28, leaving the office vacant until a successor was chosen to Benedict who succeeded John Paul, one of history's most popular pontiffs.

Since Vatican II, there has been a recognition that longer life spans meant that a pope could remain in office well into his 80's when the pressures of work and the travails of the world weighed down on him, reducing his effectiveness and allowing the bureaucracy to increase its influence in the Vatican. By clearing the way for his successors to resign rather than serve until death, Ratzinger has changed the idea of succession and strengthened the papacy.

As usual, there is no lack of potential successors. One of the Italians, who have been shut out of the papacy for nearly 40 years, is going to be favored simply because there are so many of them. That has worked against them recently as they have been unable to agree on one candidate, thus being unable to maximize their advantages.

The conclave in 2005 looked at naming a third world pope from either Latin America or Africa. But cardinals from both those regions run into problems not connected with their abilities, but their ideology. Another European may be a possibility. Cardinal Christoph Schoenborn, Archbishop of Vienna, is 68 years old, and a strong conservative. He is also been praised for his openness about sex abuse scandals that have rocked the church in the western world. He has the potential of serving twice as long as Benedict which means he would leave a much greater mark on the church.

Benedict will be remembered for his brilliant intellect and the firestorm that broke out following his quoting a 14th century Byzantine emperor who harshly criticized Islam. Muslims rioted and Benedict was forced to give a clarification.

In 2006, less than two years into his papacy, Benedict stirred ire across the Muslim world, referring in a long, scholarly address to a conversation on the truths of Christianity and Islam that took place between a 14th-century Byzantine Christian emperor, Manuel II Paleologus, and a Persian scholar.

"The emperor comes to speak about the issue of jihad, holy war," the pope said. "He said, I quote, 'Show me just what Muhammad brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached.'"

While making clear that he was quoting someone else, Benedict did not say whether he agreed or not. He also briefly discussed the Islamic concept of jihad, which he defined as "holy war," and said that violence in the name of religion is contrary to God's nature and to reason.

It speaks volumes that Benedict could be reviled for quoting someone else about Islam and saying it was wrong to use violence in the name of religion.