Programing Note: Don't miss Wolf Blitzer Reports: Popes and Presidents on Easter Sunday, April 20 at 2 p.m. ET. The 30-minute special explores the long and sometimes troubled history between the White House and the Vatican.

By Wolf Blitzer and Sean Kennedy, CNN

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(CNN) - President Barack Obama will meet with Pope Francis on Thursday at the Vatican, opening a new chapter in the centuries-long relationships between the United States and the Holy See.

While Obama has praised Francis’ focus on the poor, popes and American presidents haven’t always seen eye to eye.

With that in mind, here are five surprising encounters between the Commander in Chief and the Successor to St. Peter.

1. George Washington banned the burning of papal effigies

On the anniversary of Guy Fawkes’ Day, when a Catholic plot to assassinate the Protestant King of England was disrupted, American soldiers would often mark the day by torching a straw pope.

But just five months after George Washington took command of the Continental Congress’ army in 1775, he issued an order prohibiting the violent expression of anti-Catholic bigotry.

Washington thought the custom to be “ridiculous and childish” as well as “to be insulting (Catholics’) religion.”

Washington’s decision “spoke volumes to the Vatican. Outlawing an anti-Catholic event sent a very strong message to the papacy that the American government was not anti-Catholic,” said Candida Moss, a professor of theology at the University of Notre Dame.

2. A pope almost recognized the Confederacy

At the height of the Civil War, Confederate President Jefferson Davis wrote to Pope Pius IX, thanking him for his kind sentiments in calling for a resolution to the Civil War.

The Catholic-educated but Protestant Davis went on to ask the Pope for his recognition of the Confederate States. Throughout the war, the Confederacy had tried and failed to get recognition from other European states.

“For the Vatican, this is a very difficult situation: here they have one part of a fractured country seeking their support, and they don't often get this,” Moss said.

Pope Pius IX replied a few months later addressing Davis as “Illustrious and Honorable Jefferson Davis, President of the Confederate States of America.”

By conferring the title and honorifics on Davis, the Pope appeared to legitimatize the rebellious states. "It's a scandal all over the Union newspapers," Moss said. "This leads to the complete breakdown in ties between the U.S. and the Holy See.”

This perceived slight led Congress to explicitly ban diplomatic ties with the Vatican in 1867.

3. The Vatican helped end the Cuban Missile Crisis

With Soviet missiles in Cuba and a U.S. Naval blockade of the island in place, the Vatican secretly reached out to both sides in 1962.

Pope John XXIII issued a call privately and then on Vatican Radio to both the Soviets and Americans to compromise. Finding peace was not a sign of cowardice, the Pontiff advised.

“I’ve heard that got to (Nikita) Khrushchev,” said Cardinal Theodore McCarrick, the former Archbishop of Washington. “The Pope is looking for peace and why don’t you be the man of peace?”

The message appeared to break the ice and gave Khrushchev a way out – though the crisis lasted almost another week. The Soviets agreed to withdraw the missiles in line with American demands, and the Unites States secretly withdrew its missiles from Turkey. The Pope and the President had brought the world back from the brink.

4. The United States didn’t have a Vatican ambassador until 1984

In 1797, Congress appointed an informal representative to the Vatican to assist Americans in the Papal States, the first of 11 unofficial consuls appointed. But the country had no formal diplomatic relations in Vatican City until Ronald Reagan.

The major reason was anti-Catholic sentiment.

“(Harry) Truman said he'd like an ambassador to the Holy See, but there was a Protestant backlash,” Moss said.

Although every president from Dwight Eisenhower to the present has had a formal audience with the pope, it wasn’t until after Reagan’s 1982 visit to Pope John Paul II in Rome did formal relations with the Vatican gain traction.

In 1984, Reagan succeeding in getting his close friend, William A. Wilson, appointed as the first U.S. Ambassador to the Holy See.

5. Pope John Paul II tried to prevent the Iraq War

In the weeks before the United States invaded Iraq in 2003, Pope John Paul II dispatched a Vatican diplomat, Cardinal Pio Laghi, to the White House with an unequivocal message: Stand down.

“He went in and tried to make the case,” said John Carr, who worked for the U.S. Conference of Catholic Bishops at the time, “and the President gave the letter to an aide. In that letter was a warning about what might happen to the U.S. if it invaded, and almost all of those things have happened.”

A year after the visit by Laghi, President George W. Bush awarded John Paul II the Presidential Medal of Freedom at the Vatican.

Bush holds the record for most meetings with Popes: six.