Kate Middleton wore three poppies pinned to her black Catherine Walker outfit on Remembrance Sunday — and there’s a significant reason behind it.

The 42-year-old Princess of Wales attended two events on Nov. 9 and Nov. 10, starting with the Festival of Remembrance at Royal Albert Hall on Saturday evening, followed by Remembrance Sunday at The Cenotaph war memorial the next morning. This appearance marked an important moment in Princess Kate’s gradual return to her royal duties, following her announcement on Sept. 9 that she had finished chemotherapy, about six months after revealing her cancer diagnosis on March 22.

Standing on the Foreign Office building balcony alongside Sophie, Duchess of Edinburgh, Kate displayed three poppy pins on her coatdress. While most royal family members opted for just one, Kate’s choice to wear three was symbolic: they represent her great-grandmother’s three brothers, all of whom lost their lives in World War I, as reported by The Daily Mail.

According to The Mirror, Kate had the opportunity to view letters from her ancestors during an “emotional visit” to the Imperial War Museum in 2018. Kate began wearing three poppy pins for Remembrance Sunday as early as 2015, after having worn just one the year before, according to The Sun. She continued wearing the three-poppy set every year until 2019, when she chose to wear the Codebreakers brooch to honor her grandmother, Valerie Glassbarrow. In 2020, Kate returned to the three poppies, adding the Royal British Legion crystal flower as an accessory.

Remembrance Sunday, held on the second Sunday of November each year, is a national day of remembrance for the members of the Armed Forces in the U.K. and Commonwealth who died in conflict or war. Since joining the royal family in 2011, Kate has never missed attending Remembrance Sunday.

The poppy has been a symbol of remembrance for fallen military members since 1921. It is most commonly associated with the U.K. and Commonwealth nations for Remembrance Day on November 11, and the symbol is thought to have originated from the poem “In Flanders Fields” by John McCrae, which reflects on World War I.

The royal’s outfit on November 10 was filled with meaning, extending beyond the three poppies. She wore a coatdress by Catherine Walker, honoring her late mother-in-law, Princess Diana, who considered Walker her favorite designer and a personal friend. The night before, at the Festival of Remembrance, Kate also paid homage to Diana with her choice of Collingwood pearl earrings.

On November 10, during Remembrance Sunday, Kate wore a pair of Bahrain Pearl Drop earrings, which were a gift from Queen Elizabeth. The Queen had received the earrings as a wedding gift when she married Prince Philip on November 20, 1947. (The Princess of Wales had previously worn these significant earrings at the late Queen’s funeral in September 2022.)