Pope Francis is spending two days in Egypt at a time when Coptic Christians there are enduring ongoing attacks by Islamic militants.

At least 45 people were killed in two church bombings on Palm Sunday, a time Christians celebrate Jesus’ triumphant arrival in Jerusalem just days before solemn ceremonies mark his crucifixion. In December, a suicide bomber killed more than two dozen people at Egypt’s main cathedral before Christmas.

Despite security concerns, a Vatican spokesman said Francis would not be riding in an armored car. He’ll celebrate one public Mass, which is being held in a military-run stadium.

Francis says he hopes to offer support to Christians reeling from the attacks while also forging better relations with Egypt’s Muslim leaders. His visit comes at a key moment for Christians and Muslims in Egypt, but what impact the pope will have, if any, remains to be seen.

Papal trips are generally seen as ways to inspire the faithful, but not all are successful. Below are five trips taken by popes that are widely seen as significant by historians.

1. Pope John Paul II’s visit to Nicaragua: March 4, 1983

Pope John Paul II didn’t play the role of peacemaker as many Catholics had hoped during his visit to Nicaragua in 1983. In fact, he came across to many as something of a scolder in chief, ordering clergy to stay out of politics and calling upon Catholics to be obedient to their bishops.

The pope was caught on camera wagging his finger at the Rev. Ernesto Cardenal, a poet, priest, liberation theologian and the country’s cultural minister. At an open-air Mass, he indirectly took aim at five priests holding government posts. During the ceremony, he also became visibly upset with the unruly crowd, spurred by pro-Sandinista instigators.

He repeatedly shouted at them to be quiet.

Instead of fostering unity, many Catholics said the pope stirred division. One priest told the New York Times that the pope’s visit marked the church’s official break with the Sandinista government. ”We’ve tried hard to build bridges with the youth of this country, who are already alienated from religion,” he said. ”The Pope broke those bridges in one fell swoop.”

2. Pope Paul VI’s visit to Israel: Jan. 4-6, 1964

Months after assuming office, Paul VI became the first pontiff to set foot in Israel since St. Peter, whom Catholics consider the first pope.

It also marked the first time a pope ever rode in an airplane or even left Italy in almost two centuries.

During the 11 hours spent on the ground, the pope never once mentioned the country by name as the Vatican didn’t recognize the state of Israel at the time.

Before his death in 1978, he would become the first pope to visit every continent and was the first to visit the United States. He was not a gregarious pope, but known for his intellect and, of course, reaffirming the church’s ban on artificial birth control.

3. Pope Benedict XVI’s visit to Turkey: Nov. 28-Dec. 1, 2006

Months before visiting Turkey in 2006, Pope Benedict XVI delivered a controversial speech in Germany in which he quoted a 14th-century Christian emperor who said Muhammad, the founder of Islam, had brought the world only “evil and inhuman” things. The speech outraged Muslims, and more than 50 Islamic nations demanded an apology.

Benedict’s trip to Turkey was his first to a predominantly Muslim country since the controversy and was aimed at bridge building. Before he arrived, thousands took to the streets to protest the visit.

While in Turkey, the pope offered messages of reconciliation to Muslims and announced his support of Turkey’s bid to join the European Union. He also visited a mosque — only the second pope to ever visit a Muslim place of worship.

The trip appeared to be an important step toward mending the Vatican’s relations with Muslims.

“It didn’t take long for Pope Benedict XVI to transform himself from one of Turkey’s worst enemies to one of the country’s best friends,” Der Spiegel reported.

4. John XXIII’s visit to Loreto-Assisi, Italy: October 4, 1962

When he was 81 years old, Pope John XXIII embarked on a 450-mile trip, the longest journey of any pope in almost a century.

And he did it by train, becoming the first pontiff to ride by rail since popes lost the role as sovereign of the Papal States — territories on the Italian Peninsula — which had prompted Pope Pius IX to declare himself “a prisoner of the Vatican” in 1870.

In making the trip, John XXIII shattered the image of popes as isolationist.

He launched the visit ahead of the Ecumenical Council, which led to sweeping theological reforms. His first stop was a shrine in Loreto, followed by a visit to the Basilica of St. Francis in Assisi, where he prayed for the success of the council.

The New York Times reported, “Pope John has taken several trips outside the Vatican, but always by motorcar. The longest was that of two years ago, when he motored fifty miles to the mountain village of Roccantica, where he visited vacationing students of the seminary he had attended as a young man.”

5. Pope John Paul II’s visit to Poland: June 2-10, 1979

Pope John Paul II, the first non-Italian pope since 1523, made eight trips to his homeland, but the first was the most dramatic.

At the time, the country was still under Communist rule and the government had a tenuous relationship with the church in the predominantly Catholic country.

“When John Paul’s plane landed at Okecie Airport on June 2, 1979, church bells rang across the country, an unmistakable signal that Communist efforts to eradicate Poland’s Catholic identity had failed,” the National Catholic Reporter said.

The pope delivered 32 speeches over several days, urging bishops in Poland to remain faithful in their struggle against Communism. Throngs of people turned out wherever he went.

Upon his death in 2005, John Paul was widely credited as a catalyst in the downfall of Communism, and this visit was cited as pivotal.

“He gave Poles the self-confidence they needed” to form the Solidarity movement “as a unique alliance of workers and intellectuals,” the Guardian reported. “The dismantling of communism began there.”

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