Prince William, 40, followed in his late grandmother the Queen’s footsteps by laying a wreath at the Tomb of the Unknown Soldier in Warsaw on Thursday.
Queen Elizabeth II and the late Duke of Edinburgh did the same during their state visit to Poland in 1996.
William was greeted by a guard of honour and carried the assortment of flowers to the monument, spending around 10 minutes there before leaving.
On the wreath was a note reading: “In memory of those who made the ultimate sacrifice”.
It marked the first time that William used the Prince of Wales’s feathers, which consists of white ostrich feathers emerging from a gold coronet.
The royal also met with President Andrzej Duda at the Presidential Palace and will later visit the Hala Koszyki food hall to hear from those who have left Ukraine after Russia’s invasion last year.
William has said the two-day trip will allow him to personally thank troops and “underline” his support and gratitude for the Polish people who have aided Ukrainian refugees.
It came after he thanked British troops roughly an hour’s drive from the Ukrainian border for “defending our freedoms” by “keeping an eye on” the situation in Ukraine.
After arriving at the defence military base in the south-eastern Polish city of Rzeszow on Wednesday afternoon, the prince, dressed casually in a black puffer jacket and trousers, was shown a missile launcher.
Speaking to the soldiers, he said: “I just wanted to come here in person to say thank you for all that you’re doing, keeping everyone safe out here and keeping an eye on what’s going on.
“So, just a big thank you for what you do on a day-to-day basis.”
He added: “You’re doing a really important job out here and defending our freedoms is really important, and everyone back home thoroughly supports you.”