Thousands gathered in Vatican City as Pope Leo XIV was formally inaugurated during a historic mass ceremony marked by international diplomacy and calls for peace.

On May 18, 2025, Pope Leo XIV launched his papacy with a mass at St. Peter’s Square, where Ukrainian President Volodymyr Zelensky and U.S. Vice President JD Vance joined other global leaders to begin talks on global conflict and humanitarian priorities, Daily Mail reported.

The ceremony formally began the leadership of the Roman Catholic Church’s first American and Peruvian pope. Born in Chicago and formerly a missionary in Peru, he was elected on May 8 after a brief conclave that lasted just 24 hours.

More than 250,000 pilgrims and dignitaries were in attendance for the inauguration, taking place just three weeks after the funeral of Pope Francis on April 26. The crowd filled multiple zones managed by civil protection crews, with large displays and facilities set up across St. Peter's Square.

Pope Leo arrived in the popemobile, driving through cheering crowds waving flags of Peru, the United States, and the Holy See. Security levels mirrored those of major past ceremonies, reflecting the scale of the event and the number of attendees from around the world.

Pope's Ceremony Highlights Unity and Reform

During the liturgical ceremony, Pope Leo received key vestments symbolizing his new role. Cardinal Dominique Mamberti placed the pallium, representing his pastoral duties, around his shoulders, while Cardinal Luis Antonio Tagle placed the Ring of the Fisherman on his finger, officially sealing his papacy.

The rite of obedience, once reserved for cardinals, was updated with a broader representation of church delegates, reflecting Pope Leo's stated intention to decentralize Vatican authority. He has spoken against overly centralized power and committed to leadership grounded in humility and shared responsibilities.

In his homily, Pope Leo addressed challenges facing humanity, condemning violence, marginalization, and systemic inequality. He called for international unity and a church that could act as a force for reconciliation in a world divided by conflict and injustice.

Global Diplomats and Royalty Attend the Mass

Delegations from over 150 nations attended the event, including Spain’s King Felipe VI and Queen Letizia, Belgium’s King Philippe and Queen Mathilde, and Princess Charlene of Monaco. Grand Duke Henri of Luxembourg and EU Commission President Ursula von der Leyen were also present.

The United Kingdom was represented by Prince Edward, Duke of Edinburgh, in place of King Charles. The United States and Peru received front-row seating in recognition of the Pope’s dual heritage, with numerous American pilgrims traveling to witness the moment.

Among them was Kalen Hill, who described the experience as deeply emotional for American Catholics who often feel distant from the global church. “It is powerful for American Catholics … to be brought in and included in this community through Pope Leo,” she said.

Private Talks Center on Ukraine Conflict

Following the mass, Pope Leo held his first private diplomatic meeting, receiving President Zelensky and First Lady Olena Zelenska. The two sides discussed prospects for peace in Ukraine, with Zelensky thanking the Vatican for offering to serve as a platform for peace negotiations.

Zelensky characterized the conflict as ongoing and difficult, and a senior Ukrainian official emphasized Ukraine's ongoing willingness to pursue peace. The official noted that the opposing side, in their view, remains unwilling to reciprocate.

Later that day, Vice President JD Vance spoke briefly with Zelensky. The two leaders discussed sensitive issues, including a pending phone call between President Donald Trump and Russian President Vladimir Putin, a possible ceasefire, and updates from the war’s front lines.

Despite Past Tensions, Talks Improve

According to a senior Ukrainian source, this meeting “went better” than a tense exchange back in February at the White House. The tone at the Vatican was more constructive, with shared hopes for diplomatic progress despite political differences between the parties.

Vice President Vance, a Catholic convert who arrived in Rome on May 17, did not receive a private audience with Pope Leo. However, he did shake hands with the pontiff following the public ceremony and later visited the tomb of Pope Francis in a personal act of reverence.

While Pope Leo has publicly criticized U.S. immigration policies and shared articles challenging Vance’s positions, Vance stated in a radio interview that he would pray for the Pope regardless of disagreements. He declined to politicize papal views, expressing continued respect for the Church.

Pontiff Emphasizes Mission of Peace

Pope Leo ended the mass with a strong appeal for peace, specifically naming Ukraine and Gaza. He urged negotiations aimed at achieving what he described as a just and lasting resolution to conflicts affecting millions.

He also prayed on behalf of those suffering from war and hunger, including children, families, and the elderly. His message extended beyond geopolitics to include a moral appeal to global leaders and faith communities alike.

In his broader vision for the papacy, Leo reiterated his desire for a united church that encourages reconciliation not only within faith communities but between nations. He emphasized truth, justice, and compassion as central to his foreign policy approach going forward.