From a boy on a pony, guided by the gentle hand of Princess Diana, to a future King leading on horseback in full ceremonial dress — Prince William’s journey has come full circle.

The images capture not just the growth of a man, but the making of a monarch. Once a child learning the ropes of horsemanship under his mother’s watchful eye, William now commands the attention of millions as he rides with dignity and authority in royal processions. The transformation is striking, a powerful reminder of how tradition, duty, and Diana’s enduring influence have shaped the heir to the throne.

Last Saturday, the Prince of Wales had the honor of leading rehearsals for King Charles‘ Trooping the Colour birthday parade on June 17. Prince William, 40, took the salute at the Colonel’s Review at Horse Guards Parade in London, the last evaluation before the big day. William executed the duty as Colonel of the Welsh Guards, one of the seven regiments of the Household Division of the British Army that unite for Trooping the Colour each year.

The review was significant as Prince William’s first as ceremonial head of the Welsh Guards — just one year after performing the duty as the Colonel of the Irish Guards.

According to the British Army, only one “colour,” or flag, of the five regiments of Foot Guards can troop at a time before the sovereign during their official birthday parade each year. The Grenadier Guards, Coldstream Guards, Scots Guards, Irish Guards and Welsh Guards rotate annually and the Welsh Guards take their turn this year. Gert’s Royals notes that the Colonel of the respective regiment leads the review the week before Trooping the Colour, and Prince William also led the charge in 2022 for his now-former colonelcy of the Irish Guards — meaning he had the rare distinction of performing the Colonel’s Review in back-to-back years.

There was a reshuffling of royal roles following Queen Elizabeth‘s death in September, and King Charles succeeded his mother as Colonel-in-Chief of all seven regiments of the household division. He soon named Prince William and Kate Middleton the Prince and Princess of Wales, and officially made his eldest son the Colonel of the Welsh Guards — tying in with his title as heir — in December.

The King also made his daughter-in-law the Colonel of the Irish Guards, a fitting tribute as Kate has honored the regiment almost every St. Patrick’s Day since marrying into the royal family in 2011.

Queen Camilla also became Colonel of the Grenadier Guards, an honor that was removed from Prince Andrew last year along with his other military titles and patronages, in the same sweep.

“The purpose of the Colonel’s review is to decide that they are ready for the monarch,” an army source told PEOPLE, and Prince William’s latest review looked much like last year’s — the only clue was the plume! The prince wore a St. Patrick’s blue plume in his classic bearskin hat to match the mantle and sash of the Order of St. Patrick. This year, William swapped the feather for the Welsh Guards’ white and green version.

There was another uniform change to reflect Prince William’s new role as well. On the neckline of his red uniform — famous from his 2011 wedding day to Kate — the on the previous symbol of a shamrock for the Irish Guards was replaced with a leek, one of the Welsh Guards’ motifs.

Prince William also wore the royal cyphers of both Queen Elizabeth and King Charles on his shoulder for the Trooping the Colour rehearsal. The heir previously wore the tweak to his uniform during an investiture ceremony at Windsor Castle last month to signify his role as an aide-de-camp to Queen Elizabeth and King Charles.

Elsewhere during the June 10 rehearsal, at least three soldiers fainted in the summer heat, the Associated Press reported. Afterward, Prince William thanked everyone who came out to practice with a personal message on Twitter.

“A big thank you to every soldier who took part in the Colonel’s Review this morning in the heat. Difficult conditions but you all did a really good job. Thank you. W,” he wrote.

On Saturday, 1,500 soldiers, 300 horses and 400 musicians will come together for a patriotic display of military precision, horsemanship and fanfare. King Charles’ first Trooping the Colour as sovereign comes just six weeks after his historic coronation on May 6.