Crown Prince Frederik and Crown Princess Mary celebrated 19 years of marriage on Sunday. To commemorate their wedding anniversary, the future King of Denmark penned a personal message on Instagram.

“My wife and I have our wedding anniversary today. A very special day for both of us, as we like to mark - also with our four children,” he wrote (translated to English). “This year the day coincides with Mother’s Day. Therefore, special love for you, Mary, as a spouse and as a mother.”

“And at the same time, I would like to say happy mother’s day to all the mothers around the whole country,” Frederik added.

The Crown Prince’s romantic message accompanied a throwback photo of his wife and their daughter Princess Josephine eating ice cream. In addition to Josephine, Frederik and Mary are also parents to Prince Christian, Princess Isabella and Prince Vincent.

Queen Margrethe II’s eldest son married Australian-born Mary in 2004. According to Royal Central, the Crown Princess described her wedding day in the book Mary H.K.H. as “very overwhelming.”

“One piece of advice I got before my wedding, which I think most people get, was to enjoy it, take it all in and just be present. This was easier said than done. The day was very overwhelming,” she reportedly shared in the book.

“Adventurous, landmark and overwhelming. I had to say ‘yes’ both to the love of my life and to my new country,” Mary continued. “In addition, not only in front of our families and friends but also in front of the whole of Denmark.”