Prince William, a former Royal Air Force pilot, spoke with 20 D-Day veterans at the memorial service including centenarian Pixie Jenkins, Express.co.uk reports.
Ms Jenkins, who served in the Women's Royal Naval Service, expressed sadness that people had forgotten the "ultimate sacrifice" made by troops: "I think so many youngsters today have forgotten about the men. They look at them and think, they're old men now - to them they're just old men.
"And they're not - they are wonderful, wonderful men that went over. I salute them all."
It's been a busy week for the royal family.
Also on Thursday, the Prince of Wales and Camilla, Duchess of Cornwall attended services at Bayeux Cathedral in Normandy, France.
Prince Harry, Duke of Sussex travelled to the annual Founders Day Parade at Royal Hospital Chelsea in London, going solo without wife Meghan Markle, Duchess of Sussex who is still enjoying maternity leave with newborn Archie Harrison.
Kate Middleton was also absent from D-Day commemorations, with many speculating the Duchess stayed home with the Cambridges three young children.
On Wednesday, Her Majesty Queen Elizabeth also paid tribute to her father King George VI in a short but powerful speech which noted the "heroism, courage and sacrifice" of the soldiers who lost their lives in WWII.
Her Majesty said: "In a broadcast to the nation at that time, my father, King George VI, said - 'What is demanded from us all is something more than courage and endurance. We need a revival of spirit, a new, unconquerable resolve.'"
The Queen was joined by her son Prince Charles, British Prime Minister Theresa May and American President Donald Trump and his wife Melania to meet with World War II veterans on the final day of their state visit to Britain.
World leaders including Australian Prime Minister Scott Morrison, French President Emmanuel Macron, German Chancellor Angela Merkel and Canadian Prime Minister Justin Trudeau were also in attendance.