In a toast at a lavish state banquet held in President Trump's honor at Buckingham Palace, the Queen recognized the common bonds between the United States and the United Kingdom, even as Trump arrived swinging at London’s mayor.
"After the shared sacrifices of the second World War, Britain and the United States worked with other allies to build an assembly of international institutions, to ensure that the horrors of conflict would never be repeated," the Queen said, acknowledging the D-Day remembrance ceremonies set to take place in the coming days and the NATO alliance that formalizes the security alliance.
Though the queen used subtle language in reaffirming the security alliance, her message was unmistakable as stood beside a president who has at times stopped short of reaffirming the United States' unqualified commitment to NATO's common defense principle.
"Of course, it is not only our security which unites us, but our strong cultural links and shared heritage. Every year, there are almost 4 million visits by Americans to the United Kingdom, with a great number claiming British descent. And with your own Scottish ancestry, Mr. President, you too have a particular connection to this country," the Queen said to the president, whose mother is of Scottish heritage.
"Mr. President, as we look to the future, I'm confident that our common values and shared interests will continue to unite us. Tonight, we celebrate an alliance that has helped to ensure the safety and prosperity of both our peoples for decades, and which I believe will endure for many years to come," the Queen said with Trump sitting at her side. "Ladies and gentlemen, I invite you all to rise and drink a toast to president and Mrs. Trump, to the continued friendship between our two nations and to the health, prosperity, and happiness of the people of the United States."
The president, speaking next, said that he and the first lady -- who wore a white Dior Haute Couture gown -- are "profoundly honored" by the state visit and praised the Queen's "nearly seven decades of treasured friendship with the United States of America."
"From the Second World War to today, her majesty has stood as a constant symbol of these priceless traditions. She has embodied the spirit of dignity, duty, and patriotism that beats proudly in every British heart. On behalf of all Americans, I offer a toast to the eternal friendship of our people," Trump said.
It was a gold-plated end to a day of royal pomp and circumstance.
President Trump and the first lady were met with an 82-gun salute, half to honor the president and the other half to honor the anniversary of the queen’s coronation.
As the queen and the first lady, dressed in a Dolce & Gabbana suit with a custom hat by Herve Pierre, looked on, the president joined Prince Charles, the heir to the throne, in inspecting the Grenadier Guards wearing their traditional bearskin hats.
Ivanka Trump, the president's eldest daughter and a senior adviser as well as her husband, senior adviser Jared Kushner, watched from a palace balcony. Pageantry, pomp and circumstance were on full display throughout the ceremony which was held in a garden outside the 775-room palace.
After hosting the president inside the palace for lunch, the queen showed the first couple an exhibition of items in the royal collection that are of historical significance to the United States. Among the gifts and artifacts on display at the palace: an 18th century map of New York, old-time photos of a golfer at St. Andrews and pewter horse statuette the president gave the queen last year.
Following behind the president were Jared Kushner and Ivanka Trump, Prince Harry, National Security Adviser John Bolton, Treasury Secretary Steve Mnuchin, and White House press secretary Sarah Sanders.
The president and first lady continued their visit with a tour of historic Westminster Abbey, which doubles as a place of worship and the home of art treasures, tapestries and other artifacts. As they entered, the president greeted a line of robed clerics and officials, then placed a memorial wreath at the grave of The Unknown Warrior from World War I. A Westminster boys choir sang as the first couple stood with their heads slightly bowed.
The president penned a note in the guest book, using his signature Sharpie instead of a pen, to leave a brief message: "Thank you so much. This has been a great honor. Special place."
The visit was the first in what will be a series of events over the course of this trip to honor those who have paid the ultimate price in protecting allied values. On Wednesday, the president will participate in a D-Day commemoration event in Portsmouth and make a pilgrimage to Normandy to mark the 75th anniversary of the allied invasion.
President Trump has marveled at some of the previous elaborate welcomes he’s received during his travels abroad during his tenure in office, but his three-day state visit to the United Kingdom has been designed with the explicit intent of dazzling the visiting U.S president.
Ahead of a lavish state dinner hosted by the queen, the president offered his positive review of how his trip is going so far.
"Tremendous crowds of well wishers and people that love our Country. Haven’t seen any protests yet, but I’m sure the ... Fake News will be working hard to find them," Trump wrote.
While it is the case that the president has avoided seeing any major demonstrations on Monday, it is expected that major protests will occur on Tuesday.
The state visit invitation was first extended to the 45th president just after he assumed the presidency in 2017 but is only now coming to fruition more than two years later. He previously visited the U.K. last year, taking tea with the queen at Windsor Castle at the time, but that was during a less ceremonial working visit.
President Trump is only the third U.S. president to be honored with a state visit hosted by the queen. President George W. Bush had such a visit in 2003, as was President Obama in 2011.
While the president is expected to meet Prince Harry, he is not expected to meet his wife, Meghan. The Duchess of Sussex is not expected to attend at any of the state visit events, according to the palace, because she remains on maternity leave from her official duties as a member of the royal family following the recent birth of her son Archie.
Meghan’s excusable absence from the state visit ceremonies avoids the potential for an awkward encounter, given that both Trump and Meghan have been publicly critical of one another.
Prior to marrying into the royal family, Markle called Trump a “misogynist” during the 2016 campaign and suggested she'd be inclined to live in Canada if he were elected president. Trump recently responded to her past criticism, saying “I didn’t know that she was nasty” in an interview with the British outlet The Sun.
In addition to lunch at the palace, the queen showed the first couple an exhibition of items in the royal collection that are of historical significance to the United States. Prince Andrew acted as tour guide for the president and first lady for a visit to Westminster Abbey. There, the president laid a wreath at the grave of The Unknown Warrior from World War I.
Later that afternoon, the president and first lady were received for tea by Prince Charles and Camilla at their official residence at Clarence House. The private welcome at the prince’s home was seen as a particularly significant moment in the trip, given that the prince is next in line to the thrown behind his 93-year old mother.
To cap off the majestic day, the palace pulled out its finest china for a lavish state banquet at Buckingham palace in the president and first lady’s honor. The president, in white tie, walked into the ballroom of Buckingham Palace with the Queen at his side.
“It’s huge preparations,” says royal commentator Robert Jobson, “making sure that absolutely everything is tip-top, from the champagne that is used to even little details, what exactly each guest requires … to make sure it’s the perfect evening.”
The queen herself played a directing role in making sure the night was executed to the highest possible standards.
“The queen, before the day of the banquet, will be going around and making sure that everything is the way she wants it, that’s the way they’ll be operation, and it will be a perfect example of British hospitality,” Jobson said.
The president’s children and their spouses, who are joining the president on the state visit, joined the formal dinner, according to a White House official. Other guests included National Security Advisor Amb. John Bolton, Treasury Sec. Stephen Mnuchin, and Kellyanne Conway.
Dinner was served on an elaborate place setting that took four days to prepare. Guests dined on delicacies that included steamed fillet of halibut with watercress mouse, asparagus spears and chervil sauce, and saddle of new season Windsor lamb with herb stuffing.
After the banquet, the president and first lady will then return to Winfield House, the official U.S. ambassador’s residence, where they will be staying during their two-night stay in London. While the president and first lady might otherwise be expected to stay at Buckingham Palace, the official chief residence of the royal family is currently undergoing extensive renovations.
The second day of the state visit will be filled with more official business than ceremony, as the president heads to 10 Downing Street to be received by outgoing Prime Minister Theresa May.
The president’s visit comes at a particularly awkward moment for May, who announced her resignation last Friday and is set to officially step down as the Conservative Party leader on June 7, just a few days after the president’s visit.
The day will begin with business. President Trump attending a business breakfast meeting at St. James’s Palace co-hosted by May that will bring together major U.S. and UK business leaders.
The persistent uncertainty around Brexit will no doubt be a topic of discussion at the breakfast. While the president has expressed his hopes for negotiating a bilateral trade agreement with the UK, the president’s National Security Adviser John Bolton said the U.S. is waiting for the UK’s planned exit from the EU to occur first.
“President Trump remains very eager to cut a bilateral trade deal with an independent Britain. It’s what the people voted for in 2016, and when they get out, whether it’s now, April 12 or later, we’ll be standing right there waiting for them,” Bolton said in a recent interview with Reuters.
After breakfast, the president heads to the prime minister’s official residence at 10 Downing Street for meetings and could potentially hold a joint news conference.
In the evening, the president and first lady will reciprocate the hospitality of their British hosts with a dinner hosted at Winfield House. Prince Charles and Camilla will attend the dinner in the queen’s place, according to the palace.
On his third and final day in the UK, the president will join the queen and over 300 D-Day veterans in Portsmouth for a national ceremony of remembrance on the 75th anniversary of the allied military invasion that is remembered as a turning point of World War II.
The queen will then formally bid the president farewell from Portsmouth as he continues on in itinerary, which will take him to Ireland and France.
In France, the president will attend the ceremonies marking the 75th anniversary of the D-Day invasion on the shores of Normandy. And in Ireland, the president will have an official meeting with the Irish Taoiseach Leo Varadkar and pay a visit to one of his eponymous properties.
ABC News' Rachel Scott and Meridith McGraw contributed to this report.