The coronation of King Charles III and Queen Camilla

The third and most sacred phase of the service, the anointing, is underway.

It began with the King and Queen kneeling at the Chairs of Estate, as the choir sang in English, Welsh, Gaelic, and Irish. The Archbishop of Canterbury led a short prayer.

Now, the most dramatic part of the ceremony is starting. It is the only section that is taking place away from the crowds, cameras and sharp-eyed photographers.

What's happening: The Dean of Westminster pours holy oil from the Ampulla, a gold eagle-shaped flask, on to the Coronation Spoon, and then the Archbishop of Canterbury anoints Charles on his head, breast and hands, according to the Church of England's liturgy.

The 12th-century, silver-gilt spoon is the oldest object used in coronations, having survived the obliteration of royal regalia during the English Civil War. By contrast, the Ampulla was most likely melted down. A new one was created for King Charles II’s coronation in 1661, following the restoration of the monarchy the year before.

The anointing takes place behind a three-sided screen, hidden from view while Charles is seated on the Coronation Chair.

In the background, the Choir of Westminster Abbey sings the anthem "Zadok the Priest" by George Frideric Handel, which was composed for the coronation of King George II in 1727 and performed at every British coronation since.

Archbishop of Canterbury Justin Welby is reading a sermon, bringing the second part of the ceremony to an end.

"We are here to crown a King, and the King is crowned to serve," he said at the start of the sermon.

He honors many of those in attendance for their charity, community and military work, and singles out 400 "extraordinary young people" who have been selected to watch from nearby St. Margaret’s Church.

Sarah Mullally, Dean of His Majesty’s Chapels Royal, has read the Gospel.

The reading is bookended by a two-part composition by the prolific British composer Debbie Wiseman – best-known for her TV and film work – called "Alleluia (O Clap your Hands)" and "Alleluia (O Sing Praises)."

The second part of the work is sung by the Ascension Choir, and it's another first – the first time that a gospel choir has sung at a coronation.

Rishi Sunak, the British Prime Minister, is conducting a reading from the Bible.

It comes from the Epistle to the Colossians:

King Charles has read a prayer out loud, becoming the first monarch to do so at a coronation.

It's followed by the Gloria from the Mass for Four Voices by the Renaissance composer William Byrd.

Here's the prayer he read:

For all the television cameras, photographers and crowds, there is one moment in the coronation that won’t be broadcast around the world -- when the monarch is anointed with holy oil by the Archbishop of Canterbury, Justin Welby.

This is considered the most sacred part of the service and wasn’t televised in 1953. On Saturday, the moment is shielded by an intricately embroidered screen, designed by iconographer Aidan Hart and created through both hand and digital embroidery, managed by the Royal School of Needlework.

Welby wrote in the official souvenir program that the moment is “a symbol of being commissioned by the people for a special task for which God’s help is needed.”

He added: “It is a moment when The King is set apart for service: service of the people of this country, and service of God.”

Behind this three-sided screen, the Dean of Westminster pours holy oil from the Ampulla, a gold eagle-shaped flask, on to the silver-gilt Coronation Spoon before the Archbishop of Canterbury anoints Charles on his hands, chest and head.

Like everything else in the coronation, the screen itself is laden with symbolism. Its central design takes the form of a tree, featuring the names of all 56 Commonwealth countries on the leaves, with the King’s cypher at the base of the tree “representing the Sovereign as servant of their people,” Buckingham Palace said.

Service personnel from the Household Division – part of the British Army responsible for delivering State Ceremonial and Public Duties – will hold the screen.  

After the Recognition, the king was presented the Coronation Bible and took the Coronation Oath.

The Bible was presented by Iain Greenshields, moderator of the general assembly for the Church of Scotland, who sets the words of God – the Bible – as the "royal law" to govern with.

The presentation of the Bible dates back to the joint coronation of William III and Mary II in 1689, with the involvement of the moderator beginning in 1953, according to the Church of England's liturgy.

Before taking the Oath, Charles consented to its conditions, including fostering "an environment in which people of all faiths and beliefs may live freely." This addition to the service reflects the words of the late Queen, when she said the role of the church "is not to defend Anglicanism to the exclusion of other religions," but instead has a "duty to protect the free practice of all faiths in this country."

Then, Charles placed his hands on the Bible and promised to abide by the Oath as administered by the archbishop, swearing to govern the people of Great Britain and Northern Ireland, and the Commonwealth, while maintaining the laws of God.

Charles has been sovereign since the death of his mother, the late Queen Elizabeth II, but today he participates in the ceremonial rite of passage that accompanies being crowned king.

The coronation service starts with the Recognition, according to the Church of England's liturgy. For this symbolic moment, Charles will stand on a special platform built within Westminster Abbey called the Theatre, where he will turn to each of the four points of the compass to presents himself to the people, who will affirm and acknowledge him as the king.

Archbishop of Canterbury Justin Welby is the first of four representatives to make the declaration while facing the High Altar:

The congregation calls out, "God save King Charles," in response, recognizing him as the head of state.

The liturgy lists the other representatives as members of the oldest Order of Chivalry in England, the oldest Order of Chivalry in Scotland, and the Chair of the Victoria Cross & George Cross associations.

Justin Welby, the Archbishop of Canterbury, has begun the service.

"Dearly beloved, we are gathered to offer worship and praise to Almighty God; to celebrate the life of our nations; to pray for Charles, our King; to recognize and to give thanks for his life of service to this Nation, the Realms, and the Commonwealth; and to witness with joy his anointing and crowning, his being set apart and consecrated for the service of his people," Welby said.

"Let us dedicate ourselves alike, in body, mind, and spirit, to a renewed faith, a joyful hope, and a commitment to serve one another in love."

His introduction was followed by a rendition of "Kyrie eleison" -- the first time a Welsh-language piece of music has been performed at a coronation.