St Patrick's Day marked an important milestone for the Prince and Princess of Wales, with Kate attending the parade for the first time after taking over her husband's former position as Colonel of the Irish Guards.
Aside from the Princess' eye-catching teal coat dress and the adorable mascot Seamus, royal fans may not have noticed why the joint engagement also had a sweet link to the couple's 2011 wedding day. Take a look inside William and Kate's wedding below...
WATCH: Best moments from Prince William and Princess Kate's royal wedding
William chose to wear the Irish Guards Mounted Officer's uniform on his big day, which took place just two months after the late Queen Elizabeth II had announced his position as Colonel, which was his highest-ranking appointment.
"If he had not gone for that he would have had to have chosen between his RAF and Household Cavalry uniforms and because he is a similar rank in both of those, it would have been quite a difficult decision," explained a St. James’s Palace spokesperson.
The Prince and Princess of Wales spent St Patrick's Day with the Irish Guards
William teamed the red tunic, which the royal family's website explained had the Irish Guards' distinctive arrangement of buttons, with his Order of the Garter sash and star, the Queen's Golden Jubilee medal, and his Royal Air Force wings.
While he regularly recycles the military outfit for Trooping the Colour, the monarch's birthday parade every June, he did not wear it for his latest appearance. Instead, William – who is now Colonel of the Welsh Guard – looked dapper in his black uniform.
His younger brother Prince Harry claimed in his book Spare that the Prince of Wales was "gloomy" and "frustrated" that his grandmother had insisted he wore the bright red Irish Guards uniform on his wedding day, as it was not his first choice.
Prince William was made Colonel of the Irish Guards two months before his 2011 wedding
William reportedly asked to wear the cavalry uniform and frock coat of the Royal Guard, a request that was dismissed by Her Majesty.
Speaking to journalist Robert Hardman, who reported the exchange in the MailOnline, William said: "I wanted to decide what to wear for the wedding.
"I was given a categorical: 'No, you’ll wear this!' he said. "So you don't always get what you want, put it that way…But I knew perfectly well that it was for the best. That 'no' is a very good 'no'. So you just do as you’re told!"
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