Pope Leo holding inaugural mass at the Vatican in front of thousands as crowds chant ‘Viva il Papa’

Pope Leo XIV has formally taken up his role as leader of the Catholic Church, with a Mass in St. Peter’s Square that drew hundreds of thousands of well-wishers, including dozens of world leaders and European royalty.

In his homily, Leo said he wanted to be a servant to the faithful through the two dimensions of the papacy: love and unity.

“I would like our first great desire to be for a united church, a sign of unity and communion, which becomes a leaven for a reconciled world,” he said. The Vatican underlined this line in the English translation given to the media ahead of the speech, suggesting its centrality to the new pontiff’s address.

He added that the world “must not close itself off into small groups”. “We are called to offer God’s love to everyone in order to achieve that unity which does not cancel our differences but values the personal history of each person and the social and religious culture of every people,” he said.

“Brothers and sisters, this is the hour for love. The heart of the gospel is the love of God that makes us brothers and sisters. With my predecessor Leo XIII, we can ask ourselves today, if this criterion were to prevail in the world, would not every conflict cease and peace return?

“Let us build a church founded on God’s love, a sign of unity for a missionary church that opens its arms to the world.”

His call for unity was significant, given the polarisation in the Catholic Church in the United States and beyond. It also spoke to a desire to continue the themes of the late Pope Francis’ papacy.

In a comment seemingly aimed at the current age of the strongman leader, Leo added that he felt his role as the new head of the Catholic Church was to “shield the flock without ever yielding to the temptation to be an autocrat, lording it over those entrusted to him”.

The pontiff took his first popemobile ride through St. Peter’s Square this morning, greeting the crowds who joined presidents, patriarchs and princes for the formal installation ceremony of history’s first American pope. An estimated 250,000 people are expected to have turned out for the event.

The bells of St. Peter’s Basilica tolled as Leo waved from the back of the open-topped truck that looped slowly through the square and then up and down the boulevard.

The crowd cheered “Viva il Papa” and waved plenty of Peruvian, American and Holy See flags — representing Leo’s nationalities — mixed in with flags of other nations, banners and umbrellas to shield pilgrims from the springtime sun.

Security was tight as civil protection crews in neon uniforms funnelled pilgrims into quadrants in the piazza while priests hurried into St. Peter’s Basilica to get ready for the Mass.

Born in Chicago, the 69-year-old pontiff spent many years as a missionary in Peru and also has Peruvian citizenship. He becomes the first American pope and the first to have Peruvian citizenship.

Robert Prevost, a relative unknown on the world stage who only became a cardinal two years ago, was elected pope on May 8 after a short conclave of cardinals that lasted just 24 hours.

He replaces Pope Francis, from Argentina, who died on 21 April after leading the Church for 12 often turbulent years during which he battled with traditionalists and championed the poor and marginalised.

US Vice President JD Vance, a Catholic convert who clashed with Francis over the Trump administration’s hard-line immigration policies, led a US delegation alongside secretary of state Marco Rubio, who is also Catholic, at the Mass.

Ukrainian President Volodymyr Zelensky is also in attendance, alongside his wife, Olena Zelenska, his chief adviser Andriy Yermak and foreign minister Andriy Sybiha. Mr Zelensky’s spokesperson suggested they were open to further peace talks in Rome after the ceremony, following the success of the Ukrainian president’s impromptu meeting with Donald Trump at Pope Francis’ funeral.

Mr Zelensky and Mr Vance were seen greeting one another in the run-up to the ceremony. The pair smiled as they shook hands just a few months after they were locked in a fiery exchange in the White House, when Mr Vance accused Mr Zelensky of being ungrateful for American support for Ukraine.

The inauguration Mass is a ritual filled with symbolism that connects back to Peter, Jesus’ apostle, and his special mission as head of the Catholic Church.

No new role is conferred but Leo will receive two crucial signs of his pontificate, the “pallium” and the fisherman’s ring, marking his role as successor of Peter.

The pallium is a narrow stole-like vestment with two pendants to be worn across the shoulders, decorated with crosses representing Jesus’ wounds. It’s made of white wool in an elaborate procedure where the lambs traditionally were blessed before being sheared, just like for the similar vestments given to archbishops on their ordination.

The fisherman’s ring recalls the Gospel passage where Jesus appeared to the apostles after his resurrection, as they had spent a night fishing with no catch. He told Peter to cast in a specific spot, and the nets strained with lots of large fish, some of which the apostles then shared with Jesus in a lakeside breakfast.

An image of Peter with the net, standing for the church’s evangelisation mission and its unity, is engraved on the ring alongside the pope’s name. When a pope dies, the ring is crossed over so it can no longer be used as a seal for papal documents. Cardinal Luis Tagle of the Philippines, who was widely regarded as a papal contender, will present Leo with the ring.