London - When Prince Harry and Meghan Markle stand before the altar at St. George's Chapel at Windsor Castle, a refuge of the British monarch for a thousand years, the Archbishop of Canterbury will tie the knot with vows from the Common Book of Prayer that read "to have and to hold ... until death do us part."
Not so very long ago, this wedding - with this service and this officiant at this place - would have been impossible.
Not because Markle is an American and a commoner, marrying a prince now sixth in line for the throne. And not because the actress is biracial, raised Episcopalian and attended a Catholic school in Los Angeles.
No, such a service would have been opposed by the Church of England hierarchy because Markle is divorced and her former husband, Hollywood producer Trevor Engelson, is still alive.
"That would have been a no-no," said Andrew Goddard, an Anglican priest at St. James the Less in London and an authority on the history of Christian attitudes toward marriage.
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Even though the Anglican church was founded by a king wanting to rid himself of his queen, the British royal family and the religion it heads have been struggling with divorce and remarriage for centuries.
"It's not until the last half of the 20th century that divorce becomes common and the stigma begins to fall away," Goddard said, adding that there are still traditionalists in the Church of England who believe that "marriage means forever," full stop.
Harry and Markle's ceremony on Saturday will be the first full-blown royal wedding of a divorced partner to take place with the loving embrace of the fusty English church.
President Franklin D. Roosevelt in conversation with King George VI while Eleanor Roosevelt and Queen Elizabeth exchange pleasantries at Union Station on June 8, 1939. Picture: Courtesy of the FDR Presidential Library & Museum
Rather than voice opposition, or negotiate compromise the Archbishop of Canterbury expressed his joy at the upcoming nuptials. "I am so happy that Prince Harry and Ms Markle have chosen to make their vows before God," said the Most Reverend Justin Welby.
The Daily Mail's chief royal correspondent broke the news that Welby baptized Markle using holy water from the River Jordan in a "secret ceremony" in March at the Chapel Royal, with Harry by her side. A quiet confirmation followed - which allows Markle to take communion.
This is a historic moment for a bedrock British institution. Church and crown, at various points, have resisted its arrival. But the House of Windsor has also generated a century's worth of headlines - and teachable moments - about adultery, separation, divorce and remarriage. Embarrassing as their scandals have been, the royal family's lapses have mirrored those in greater British society, and some say helped the church leadership to modernize.
Americans tend to forget - the British less so - that Queen Elizabeth II is not only the sovereign but the "supreme governor" of an official state religion, the Church of England.
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At her coronation in 1953, church officials draped her in the Imperial Robe and placed in her hand the Sovereign's Orb, brought to her from the altar at Westminster Abbey, a cross above a globe that represents, according to the Crown Chronicles, "'Christ's dominion over the world,' as the Monarch is God's representative on Earth."
Her role may be mostly ceremonial, but it's far from meaningless. The queen still approves the appointments of each bishop in her church. She's not divine, she's not a British pope, but Elizabeth's many titles include "Defender of the Faith," passed down to her from Henry VIII.
Henry, you may recall, had six wives. As the ditty goes: One died, one survived, two de-wedded, two beheaded. When he broke with the pope and declared himself head of a new church in 1533, it was because he wanted to "annul" his first marriage to Catherine of Aragon, who had failed to produce a male heir. (Henry's remains rest in St. George's Chapel, right below Harry and Meghan's feet, alongside Jane Seymour, the only one to give him a legitimate son.)
What was permitted for Henry, however, wasn't okay for just anyone, including - or especially - other royals.
Oliver O'Donovan, a scholar-priest who taught at Oxford and Edinburgh, offered coffee and biscuits and an hour's tutorial on divorce in the den of his home in Scotland.
O'Donovan explained that the Church of England was very much opposed to divorce from the medieval age to the 19th century. Asked what British marrieds with irreconcilable differences did back in the day, O'Donovan raised an eyebrow and said, "I should think of mistresses and poison."
Couples wishing to formally divorce needed an Act of Parliament. This was a rich man's game. In her essay "The Heartbreaking History of Divorce" in Smithsonian magazine, historian Amanda Foreman reports that before 1857 and the passing of new laws on ending marriage, only 324 couples successfully petitioned for divorce - and only four instances were initiated by women.
Even after divorce became legal, remarriage remained a thorny question.
In 1936, Edward VIII, a popular royal and notorious playboy, abdicated the throne when his proposed marriage to Wallis Simpson, a twice-divorced American, could not be reconciled with his role as head of the Church of England.
Edward's brother, George VI, ascended, to be followed by daughter Elizabeth.
The queen is a devout Christian. She's also a model of matrimonial endurance, married for 70 years. And she tried mightily to avoid echoes of her uncle's scandal.
In 1953, not wanting to be seen as condoning divorce, she withheld her approval of the hoped-for union between her sister, Princess Margaret, and the divorced Capt. Peter Townsend. Elizabeth later worked out a deal whereby Margaret could relinquish her place in the line of succession to the throne, thus avoiding the need for the queen to sign off. The Church of England would not officiate - Margaret would marry at a government register's office in London. In the end, Margaret let Townsend go (though she did wed and subsequently divorce, too).
It wasn't until 2002 that the Church of England's conservative governing body, a synod composed of clerics, bishops and laity, accepted - after three failed attempts dating back to the 1960s - that divorce is a sad reality of the modern age and allowed its priests to offer second and even third "further marriages" in "exceptional cases" to divorced members whose former spouses were alive.
The "exceptional" is now routine.
Britain's divorce rates are about the same as in Europe and the United States. The Office of National Statistics says 4 in 10 marriages in England and Wales end in divorce, although the rate is down from its peak in 1992. (Why? Mostly because there are more singles and more couples living together out of wedlock.)
Three of Queen Elizabeth's four children have divorced: Princess Anne in 1992. Prince Andrew in May 1996 (though he and Sarah Ferguson are rumoured to remain very, very close). And later that year, after a string of infidelities, tabloid exposes, leaked tapes, tell-all biographies and separation, Prince Charles and Princess Diana finally divorced, with the queen's blessing (or, according to Diana's allies, insistence).
Anne and Charles have remarried - but not in the style that will be afforded to Harry and Meghan.
In 1992, Anne wed her second husband, British naval commander Timothy J.H. Laurence, in a private service before 30 guests at Crathie Church near the royal Balmoral Castle in Scotland. Notably, Elizabeth is not head of the Scots church.
In 2005, Charles married his longtime love, Camilla Parker Bowles, also divorced. They took their vows in a civil service and afterwards received a blessing by the archbishop of the Church of England.
Robert Lacey, a royal biographer, said divorce today is not the crisis it once was, even for the "totemic, idealized" royal family who in the past were expected to be "the last to surrender."
As evidence, Lacey points out that Britain's royally obsessed tabloids have mostly given Markle's divorce a pass: "You can see from reaction of our most popular and troublemaking newspapers the fact that it remains a mystery as to why Ms. Markle's marriage to Mr. Engelson ended when it did - nobody is digging very deep."
"The monarchy changes with the times," said Dickie Arbiter, the queen's former press secretary. "The fact that Harry is marrying a divorcée who has a living spouse, who is biracial, whose parents are divorced, is just the way things have moved on."
He added, as a practical matter, "You also have to recognize that Harry is No. 6 in line to the throne, so is quite far removed from the thought of him ever having to become king" - and supreme governor of the Church of England.
O'Donovan, who was involved in the Church of England's drafting of new rules for remarriage in 2002, said he thinks the Anglicans got it right now: "The church defends marriage. It is a solemn, lifelong commitment. Those are the vows but . . . "
He quotes from the House of Bishops, that some marriages do fail, not by chance or accident, but "the fruit of lovelessness and carelessness" and that for a person to be married again in the church they must "search themselves honestly" and come to a mature understanding why the break occurred.
"The idea is that this is an opportunity for growth," the priest said, and not pat explanations, such as "we just grew apart."
Mark Burkill, the vicar at Christ Church in Leyton and a leader of an evangelical movement within the Church of England, is among the holdouts.
"I have never in the 34 years of my ministry remarried a divorced person in church. When people have come to me seeking this, I have explained that I want to uphold the lifelong commitment involved in marriage and that it is very difficult to properly assess individual cases," he said. Instead, he offers a service of blessing on a marriage after a register office ceremony.
Burkill said requests for church weddings at his inner-city London parish "has massively declined over the years. I feel now that I want to focus more on encouraging those living together to get married!"
Prince Harry and Meghan Markle are among those who have been cohabiting - in their case, in Nottingham Cottage on the grounds of Kensington Palace.
The Archbishop of Canterbury said he has been counselling and praying with the couple, and all requirements have been met to launch this further marriage.
He told ITV news, "Unlike recent weddings, I must not drop the ring. And I must not forget to get the vows in the right order, as I did at the rehearsal for one of my children's weddings."