Prince William and Kate Middleton were joined by Prince Harry and Meghan Markle for a walkabout outside Windsor Castle.
The throngs of onlookers erupted into cheers and applause as the foursome strolled out of the gate together on Saturday.
Despite the strained relations between the couples, the joint appearance signaled a united front in the wake of Queen Elizabeth II's death at the age of 96 on Thursday.
The brothers were both clad in navy blue suits with dark ties while their wives wore black dresses. The four walked side-by-side as they viewed the piles of flowers, notes and tributes that had been left outside the gate by members of the public.
The Sussexes held hands and at one moment wrapped their arms around each other. Kate was seen gently patting William on the back during the outing.
William, 40, and Kate,40, who recently received the titles of the Prince and Princess of Wales, and Prince Harry, 37, and Duchess Meghan, 41, then walked over to the barricades to greet the crowd of mourners. William and Harry were seen chatting at one point before going their separate ways to speak with their supporters.
Kensington Palace told People magazine that William had extended the invitation for Harry and Meghan to join him and Kate on the outing.
A source told the outlet that security were not aware that both couples would be making an appearance together.
Despite exiting outside the castle in separate cars, the foursome left together in a car that was driven by William.
Royal journalist Omid Scobie tweeted, "The Waleses had always been scheduled to greet well-wishers at Windsor Castle, but royal sources say the decision to invite the Sussexes was made in the eleventh hour.
"It is, without a doubt, a significant moment in the history of the relationship between the two brothers."
He shared a video of the reunion in another tweet, writing, "After chatting, hugging and sharing sympathies with members of the public for over 40 minutes, the Prince and Princess of Wales and the Duke and Duchess of Sussex have headed back into the Windsor Estate together."
The appearance marked the first time that the couples had been seen together since Commonwealth Day service. Tensions have been simmering between the four since Harry and Meghan stepped down from their royal roles in 2020.
The feud has reportedly been further exacerbated by accusations of racism against an unnamed royal family member that were made by Harry and Meghan in a 2021 television special hosted by Oprah Winfrey.
Upon hearing of the queen's grave condition on Thursday, the brothers took separate flights to Balmoral Castle. Prince William was accompanied by Prince Andrew, Prince Edward and Edward's wife Sophie, Countess of Essex on a Royal Air Force Jet while Harry took a flight on a commercially-leased plane.
Royal reporter Neil Sean expressed his doubts that the joint appearance meant that the relations between the couples had been fully repaired.
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He told Fox News Digital, "This was a shock to many, however instigated by King Charles as a form of unity. No trust, but a united front and as many will see Meghan was playing the demure royal role."
Neil continued, "However the crowd were receptive, which was amazing given what she has said about the media and the British public. Moving forward, this could come back to haunt the start of the reign of King Charles as the Brits simply don’t trust both Harry and Meghan."
"Even now we are wondering if all of this will hit some kind of reality TV show," he added. "If this is her second chance, we are stunned ,but let's face it. This is a woman who dumped her own family and father and recently stated that Harry has lost his too."
He noted that the appearance demonstrated "nothing" but the graciousness of William and Kate.
"Is this the ice thawing? Not according to my sources but in this difficult time, the British royals have shown they are the bigger person. Now, can Meghan forgive the royals, which is what she had printed only last week."
He observed that there was "zero body language" between Kate and Meghan, which he said was the "bigger problem".
"The story is far from over," Neil concluded.
