LONDON - British King Charles III has been crowned at Westminster Abbey in London, in a lavish ceremony not seen for seven decades.

The coronation is, at its heart, a religious ceremony, and Charles swore to defend the Church of England and to ensure that all sovereigns, himself included, are and will always be Protestant. But in a break from tradition, religious leaders from other faiths, including Hinduism, Islam, Sikhism and Judaism, played a prominent part in the proceedings — an effort to represent the diversity of modern, multicultural Britain as well as countries in the Commonwealth. Non-Christian leaders presented the less overtly religious items of regalia to the king ahead of the official coronation, and female clergy also played a more prominent role than in years past.

For the first time, members of the public were invited to take part in a “chorus of millions of voices.” The pledge of public allegiance to the king intended to replace the traditional Homage of the Peers, in which aristocrats and hereditary peers lined up in the abbey to kneel in front of the monarch and make vows of fealty. Though the invitation was meant as a democratizing gesture, it has drawn criticism on social media.

In another, less significant, update for the modern era, Charles and Camilla travelled to Westminster Abbey in the newer horse-drawn Diamond Jubilee State Coach, rather than the antique Gold State Coach, which, according to the BBC, even Queen Victoria complained was uncomfortable. They did, however, make their return in the older model, which resembled an even more gilded version of Cinderella’s carriage.

Tens of thousands of people packed the streets of London on Saturday to witness the once-in-a-generation event of King Charles III's coronation.

Britain's new monarch was greeted with a sea of red, white and blue as admirers waved Union Flags during the procession ceremony from Buckingham Palace to Westminster Abbey.

However, not everyone was feeling so jubilant about the occasion, with the Metropolitan Police arresting a number of anti-monarchist protesters, confiscating a number of placards reading "Not my King".

Whatever your allegiance, Saturday 6 May was a rare moment in modern history – the UK's first coronation since 1953.

After years of family tensions, Prince Harry attended his father’s coronation alone. Harry’s wife, Meghan, the Duchess of Sussex, is staying at home in California with the couple’s children, Prince Archie, who turns 4 on Saturday, and 1-year-old Princess Lilibet. Relegated to the equivalent of the table at the far end of the room at a wedding reception, Harry was seated in the third row of the abbey, next to Jack Brooksbank, the husband of his cousin, Princess Eugenie.

Seated in the front row were Prince William, Charles’s heir, and his wife, Catherine, the Princess of Wales, wearing ornate formal robes to reflect their rank in the royal family. The king’s sister, Princess Anne, was similarly clad. Harry wore a regular gray morning suit, adorned with his military service medals. Prince Andrew, the disgraced second son of Queen Elizabeth II, wore ceremonial robes despite no longer being a working member of the royal family.

It was a moment Charles would have anticipated most of his life, and the first time Britain has crowned a monarch in 70 years.

The congregation at Westminster Abbey proclaimed "God Save the King" as Archbishop of Canterbury Justin Welby placed the St Edward's Crown on Charles’ head – symbolising his ascension to the throne.

International royalty, head of states and governments, British politicians and celebrities were also among the approximately 2,300 people in attendance at the coronation ceremony at Westminster Abbey. Among them were the American first lady, Jill Biden, and Ukraine’s first lady, Olena Zelenska, and former prime ministers Boris Johnson, Theresa May and Tony Blair. The current British prime minister, Rishi Sunak, gave a reading from the first chapter of the Epistle to the Colossians.

Prince William kisses the king

Britain's newly-crowned monarch looked emotional as his eldest son William, the Prince of Wales, kissed his cheek after his coronation.

Kneeling before his father in a tender moment, the heir apparent said: “I, William, Prince of Wales, pledge my loyalty to you and faith and truth I will bear unto you, as your liege man of life and limb. So help me God.”

The singers Lionel Richie and Katy Perry, the composer Andrew Lloyd Webber, and the actors Judi Dench and Emma Thompson were present. The guest list spoke to Charles’s efforts to embrace a modern, multicultural Britain, but also to the monarchy’s dynastic identity.

British fashion designers were some of the stars of the sartorial show. Ms. Perry, who is performing at the coronation concert on Sunday, wore bespoke Vivienne Westwood — a national treasure but an interesting choice given the late designer’s feelings about the monarchy.

One of the standout outfits was worn by 8-year-old Princess Charlotte, daughter of Prince William and Catherine, Princess of Wales, whose white cape and dress and diamanté floral headband were all by Alexander McQueen, and made to match her mother’s dress and floral headpiece. McQueen, which is designed by Sarah Burton, also made Catherine’s wedding dress and often dresses her for major public occasions.

Camilla’s coronation dress, made of white silk and embroidered in gold and silver, with daisy chains, forget-me-nots and scarlet pimpernels to represent the love of the British countryside she and Charles share, was designed by Bruce Oldfield, one of her favorite designers (and also, as it happens, a favorite of Princess Diana). Her diamond necklace was the same one worn by Queen Elizabeth II for her coronation.

The London weather didn’t deter the crowds or the chants

Despite the rain, thousands of people lined the route, many waving Union Jack flags, as King Charles and Queen Camilla traveled from Buckingham Palace to Westminster Abbey along the Mall. Their journey was accompanied by a new “coronation march” by the film composer Patrick Doyle, who said that it “at times reflects aspects of His Majesty’s own character.”

Not everyone in Britain was excited about the coronation, especially during a cost of living crisis that has left many Britons struggling. From staunch anti-monarchists to those who feel that the royal family is out of touch with modern Britain, many creative alternative events were planned to mark the occasion.

At protests along the Mall in central London, demonstrators chanted, “Not my king,” as some others shouted, “God save the king,” in response. Some protesters were arrested. The Metropolitan Police, Britain’s largest force, which covers the Greater London area, has faced criticism for deploying what some see as heavy-handed measures to police the coronation.

After the coronation, the procession from Westminster Abbey to Buckingham Palace was greeted by cheering, if very soggy, crowds. Featuring 19 military bands and 4,000 troops, the parade stretched a mile from the palace gates. Chants of “God save the king!” erupted as Charles, Camilla and other members of the royal family appeared on the palace's balcony for a flyover of helicopters and the Red Arrows, the aerobatics team of the Royal Air Force, in a display pared back because of the quintessential British spring weather.

The king faces a test to sustain the mystique of his mother, Queen Elizabeth II, and keep the monarchy relevant in the modern era.

The Coronation of King Charles III

The British monarch acceded to the throne last September, after being the designated successor for longer than anyone in the history of the British crown.

- Walking a Tightrope: King Charles III is said to want a more accessible, forward-looking and inclusive monarchy. It’s not an easy message to convey through golden relics and ancient rituals.

- Why the Monarchy Persists: As long as there has been a monarchy, there have been questions about its legitimacy. But for many people, it is difficult to disentangle the royal family from British identity.

- The King’s Realms: Many of the former colonies that still formally swear allegiance to King Charles III are accelerating efforts to cut ties with the crown and demanding a deeper reckoning with its colonial history.

- Effect on the Economy: Caught between slow growth and high inflation, businesses are hoping that the coronation will increase consumer confidence. But will that be enough?

- Charles’s Love of the Arts: In King Charles III, Britain has its most culturally attuned monarch in generations. Here is a look at his interests and tastes.

- On the Menu: Move over, coronation chicken. Britain is celebrating the crowning of Charles with a new take on a traditional fish pie and a divisive vegetarian quiche.