VATICAN CITY — Pope Leo XIV, the Catholic Church’s first American pope, pledged on Sunday to strive for unity, aiming for the Church to stand as a beacon of peace worldwide. This pledge was delivered in a message of communion during the inaugural Mass at St. Peter’s Square, witnessed by an estimated 150,000 pilgrims, leaders, and dignitaries.

Leo officially commenced his papacy with his maiden popemobile ride through the piazza, a rite emblematic of the papacy’s broad global influence and media appeal. Smiling and waving from the vehicle, the 69-year-old Augustinian missionary did not stop to kiss babies or interact closely with the crowd.

During the Mass, Leo appeared to choke up when the two potent symbols of the papacy were placed on him — the pallium woolen stole over his shoulders and the fisherman’s ring on his finger — as if the weight of responsibility of leading the 1.4-billion strong church had just sunk in.

He turned his hand to look at the ring and seal and then clasped his hands in front of him in prayer.

U.S. Vice President JD Vance, one of the last foreign officials to see Pope Francis before he died, led the U.S. delegation honoring the Chicago-born Leo after paying his respects at the Argentine pope’s tomb upon arriving in Rome late Saturday.

In his homily, Leo said he wanted to be a servant to the faithful through the two dimensions of the papacy, love and unity, so that the church could be a force for peace in the world.

“I would like that our first great desire be for a united church, a sign of unity and communion, which becomes a leaven for a reconciled world,” he said. “In this our time, we still see too much discord, too many wounds caused by hatred, violence, prejudice, the fear of difference, and an economic paradigm that exploits the Earth’s resources and marginalises the poorest.”

His call for unity was significant, given the polarization in the Catholic Church in the United States and beyond.

Francis’ radical 12-year pontificate, which emphasized care for the poor and marginalized and disdain for the capitalist economic system, often alienated conservatives and traditionalists. Leo’s May 8 election, after a remarkably quick 24-hour conclave, has appeared at the outset to have pleased conservative Catholics who seem to appreciate his more disciplined, traditional style and Augustinian background, emphasizing core truths of Catholic doctrine.

“Let us build a church founded on God’s love, a sign of unity, a missionary church that opens its arms to the world, proclaims the word, allows itself to be made restless by history, and becomes a leaven of harmony for humanity,” Leo said, referencing some of the themes of Francis’ pontificate as well.

At the end of the Mass, Leo expressed hope for negotiations to bring a “just and lasting peace” in Ukraine and offered prayers for the people of Gaza — children, families and elderly who are “reduced to hunger,” he said. Leo made no mention of hostages taken by Hamas from southern Israel on Oct. 7, 2023, as Francis usually did when praying for Gaza.

Strict diplomatic protocol dictated the seating arrangements at the inaugural Mass, with both the United States and Peru getting front-row seats thanks to Leo’s dual citizenship. Vance, a Catholic convert who tangled with Francis over the Trump administration’s mass migrant deportation plans, was joined by U.S. Secretary of State Marco Rubio, who arrived in Rome ahead of time to try to advance Russia-Ukraine peace talks.

Peruvian President Dina Boluarte is one of around a dozen heads of state attending, as well as Ukrainian President Volodymyr Zelenskyy. Russia was represented by the culture minister, Olga Liubimova.

After the Mass, Leo greeted the delegations one-by-one in the basilica and had proper audiences scheduled Sunday with Zelenskyy and Boluarte.

Diplomatic protocol also dictated the dress code: While most wore black, the handful of Catholic queens and princesses — Charlene of Monaco and Letizia of Spain among others — wore white in a special privilege allowed them. Three dozen of the world’s other Christian churches sent their own delegations, the Jewish community had a 13-member delegation, half of them rabbis. Other representatives headed Buddhist, Muslim, Zoroastrian, Hindu, Sikh and Jain delegations.

Security was tight, as it was for Francis’ funeral on April 26, which drew an estimated 250,000 people. The Vatican said 150,000 were on hand Sunday in the piazza and surrounding streets, parks and piazzas, where giant television screens and portable toilets were set up.

U.S. seminarian Ethan Menning, 21, from Omaha, Nebraska, wrapped himself in an American flag, purchased at a truck stop in Iowa, to celebrate.

“Rome always felt like home for a Catholic, but now coming here and seeing one of our own on the throne of Peter … it almost makes Jesus himself more accessible,” he said.

Kalen Hill, a pilgrim from the U.S., got to St. Peter’s soon after the gates opened at dawn Sunday morning and said he never expected an American would lead the church.

“I would say all the Americans are emotional about it,” he said. “It is really powerful for American Catholics who sometimes feel separated from the world church to be brought in and included in this community through Pope Leo.”

The two symbols of the papacy handed to Leo were the pallium, and the fisherman’s ring. The pallium, draped across his shoulders, symbolizes the pastor carrying his flock as the pope carries the faithful. The ring, which becomes Leo’s official seal, harks back to Jesus’ call to the apostle Peter to cast his fishing nets.

The other symbolically important moment of the Mass was the representational rite of obedience to Leo: Whereas in the past all cardinals would vow obedience to the new pope, tmore recent papal installations involve representatives of cardinals, bishops, priests, deacons, nuns, married couples and young people participating in the rite.

Gregory and Susan Hudak, who lived for 40 years in the Chicago area, found themselves in Rome after booking a trip in February, with just a faint hope of perhaps glimpsing the pope. Seeing the popemobile pass by in front of them, with the Chicago-born Leo on board, was even better than watching Michael Jordan play, said Gary Hudak, a former altar boy wearing a Chicago Bears hat.

“Originally, the only hope I had coming here was to see the inside of the Sistine Chapel,” he said. “Seeing the pope was not scheduled, it was a long shot hope. And this was a treasure, simple as that.”

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