President Trump visits the American cemetery in Normandy.

President Trump will mark the 75th anniversary of the D-Day invasion in Normandy at a ceremony at the grave site of more than 9,380 American service members who were killed in the World War II landings and the operations that followed. Later, he will meet with President Emmanuel Macron of France in Caen, a city that was heavily bombed during the invasion.

“We are gathered here on freedom’s altar,” Mr. Trump will say, according to advance excerpts from his planned speech at the American military cemetery in Normandy. “On these shores, on these bluffs, on this day 75 years ago, 10,000 men shed their blood — and thousands sacrificed their lives — for their brothers, for their countries and for the survival of liberty.”

Mr. Trump and the first lady emerged from the president’s military helicopter just before 11 a.m., their arrival shown on two screens flanking the large stage. Cheers erupted from the audience for Mr. Trump, with some audience members taking off their caps and waving them.

At the ceremony, Mr. Trump will honor the lives lost in the operation, and also nod to the military partnerships between the Allied nations involved that made the D-Day landings successful.

“Today, we remember those who fell here, and we honor all who fought here,” he will say, according to the prepared remarks. “They won back this ground for civilization.”

Of the nearly 160,000 Allied troops who landed on Omaha, Juno and the other beaches of northern France or parachuted behind German lines, about 73,000 were from the United States. More than two million troops from 12 countries, including soldiers, pilots, medics and other personnel, took part in the battle for western France, called Operation Overlord.

“To all of our friends and partners — our cherished alliance was forged in the heat of battle, tested in the trials of war and proven in the blessings of peace,” Mr. Trump will note. “Our bond is unbreakable.”

French and U.K. leaders unveiled a new memorial to British troops.

Mr. Macron and Prime Minister Theresa May of Britain visited a new British war memorial at Ver-sur-Mer, a small coastal town in Normandy, on Thursday for a ceremony on the anniversary of D-Day.

Mr. Macron said that the monument, which is under construction, would be a “powerful symbol of the ties uniting our two nations” and a fitting tribute to the 22,000 soldiers under British command who died in the battle for Normandy.

“Nothing will ever erase these ties made of shed blood and shared values,” Mr. Macron said, adding, in an apparent reference to Britain’s drawn-out and bitter withdrawal from the European Union, that “the debates of the present take nothing away — on the contrary — from the strength of our shared history and our common future.”

“Whatever it takes, we will always stand together, because this is our common destiny,” Mr. Macron said, also expressing his “friendship” toward Mrs. May, who will soon step down as prime minister. Mrs. May also spoke, praising the soldiers not only for their military actions, but for what they represented.

“These young men belonged to a very special generation, the greatest generation, a generation whose unconquerable spirit shaped the postwar world,” she said. “They didn’t boast. They didn’t fuss. They served. And they laid down their lives so that we might have a better life and build a better world.”

Later on Thursday, Mr. Macron met in Bayeux with two French veterans, Léon Gautier and Jacques Lewis, both of whom took part in the D-Day landings. About 3,000 French troops took part in the Overlord operation, including 177 Marines who landed on the beaches.

Nearly 3,000 French civilians in Normandy were killed on D-Day, almost as many as the number of Allied troops who died that day.

Tweets reflect the president’s split-screen presidential persona.

Shortly before leaving Ireland for the D-Day commemoration in Normandy, Mr. Trump tweeted about a matter of utmost importance to him — his media coverage.

The trifecta of tweets was in keeping with the split-screen rendition of the presidency that Mr. Trump delivered during the first three days of his European trip. He toggled back and forth between insulting a celebrity and a senator on Twitter and offering warm words of appreciation to some of the few remaining veterans of World War II and mingling with the British royal family.

As he prepared to board the plane for France on Thursday morning, Mr. Trump stopped to discuss tariffs on Mexican and Chinese imports, and to bash Democrats over immigration laws.

“Mexico was in yesterday. They’re coming back this morning,” said Mr. Trump, who has threatened to impose a 5 percent tariff on Mexican imports starting Monday in a bid to force the neighboring country to take additional measures to curb the flow of Central American migrants crossing the United States’ southwestern border.

“They have to step up to the plate — and perhaps they will,” he said. Mr. Trump also said that was prepared to impose “at least $300 billion” in additional tariffs on goods from China, “and I’ll do that at the right time.”

He said that Democrats in Congress had been “a disaster,” adding, “They want free immigration. They want immigration to pour into our country.”

Then he turned to leave, saying: “I think China wants to make a deal badly. I think Mexico wants to make a deal badly. And I’m going to Normandy.”

Normandy is not a place for ‘anything political,’ John Kerry said.

John Kerry, the former secretary of state and Vietnam veteran, was among the dignitaries who arrived before the ceremony began in Normandy.

Mr. Trump has previously said that Mr. Kerry — who was a key negotiator in the Iran nuclear deal — should be prosecuted for discussions with Iranian officials after he left office. But Mr. Kerry waved away questions about politics when asked about the president on Thursday.

“This is not a place to talk about Democrat or Republican or anything political,” Mr. Kerry told a small group of reporters near the security tent.

“We have a challenging world and this place, to me at least, is a statement about sacrifice and commitment” to solve those problems, he said.

Mr. Kerry laid out what was on the line during the Normandy invasion.

“It’s about the bigger issue of what was at stake in that moment when tyranny, fascism, a lack of tolerance” were “being used to separate people, to kill people and to divide a world in a very different way than the way people in democracies have grown up feeling is a better approach,” Mr. Kerry said.

The diplomacy goes on, with France’s president next.

Mr. Trump is scheduled to hold talks with Mr. Macron on Thursday, after the D-Day anniversary events in Normandy.

The two leaders once had a warm relationship — characterized by effusive mutual praise and long, much-scrutinized handshakes — but it has chilled in recent months as their disagreements have widened on issues like climate change and the nuclear accord with Iran. Mr. Macron has also tried to position himself as the leader of Europe’s centrists and moderates, directly opposed to the nationalists and populists who have found common cause with Mr. Trump on trade and immigration.

Mr. Trump met with another leader he has disagreed with, Chancellor Angela Merkel of Germany, on Wednesday, on the sidelines of the Portsmouth ceremony. A spokeswoman for the chancellor said they had discussed the political situation after the European Parliament elections — in which populists and nationalists increased their share of seats — and security issues in North Africa.

The president also spoke with Prime Minister Leo Varadkar of Ireland before going to his golf club on Ireland’s western coast. In brief remarks to reporters, Mr. Trump suggested that they would discuss Brexit, alluding to the problem of the border between Ireland and Northern Ireland that has haunted the debate over Britain’s withdrawal from the European Union.

“We have a border situation in the United States, and you have one over here,” he said. “And I think it will all work out very well, and also for you with your wall, your border.”

Mr. Varadkar interjected, noting that Ireland did not want a physical barrier. “I think one thing we want to avoid, of course, is a wall or border between us,” he said.

Mr. Trump said he understood: “The way it works now is good, and I know you want to try to keep it that way. I know that’s a big point of contention with respect to Brexit and your border.”

Mark Landler, Maggie Haberman, Aurelien Breeden, Alan Yuhas and Michael Wolgelenter contributed reporting.