Royals Kate Middleton and Prince William Join Other Royals at Festival of Remembrance — Complete with Poppy Pins Queen Elizabeth missed the event but plans to attend Sunday's service By Stephanie Petit Stephanie Petit Stephanie Petit is a Royals Writer and Reporter at PEOPLE. People Editorial Guidelines Published on November 13, 2021 04:41 PM Share Tweet Pin Email Photo: Geoff PUGH/POOL/AFP via Getty Kate Middleton and Prince William took part in an annual tradition ahead of Remembrance Sunday. The couple, both 39, joined fellow members of the royal family on Saturday evening at London's Royal Albert Hall for the Festival of Remembrance, a yearly musical tribute to remember Britain's fallen soldiers. Royals in attendance included Prince Charles and Camilla, Duchess of Cornwall, Prince Edward and Sophie, Countess of Wessex, Princess Anne and Vice Admiral Sir Tim Laurence, the Duke and Duchess of Gloucester, the Duke of Kent, and Princess Alexandra. Missing from the event was Queen Elizabeth. The monarch, 95, has canceled several engagements after being hospitalized on Oct. 20 and subsequently told to rest by doctors. However, she plans to attend Sunday's service at the Cenotaph war memorial. Why Everyone in the Royal Family Is Wearing a Red Poppy Pin This Week Following tradition, the men wore suits while the women dressed in black. All adorned their outfits with red poppy pins, the symbol that has been used since 1921 to commemorate military members who have died in war. Geoff PUGH/POOL/AFP via Getty The poppy symbol is believed to have come from the poem "In Flanders Fields" by John McCrae, a poem about World War I. The opening stanza reads: In Flanders fields the poppies blowBetween the crosses, row on row,That mark our place; and in the skyThe larks, still bravely singing, flyScarce heard amid the guns below. Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! Geoff PUGH/POOL/AFP via Getty This year's event marks the centenary of the Royal British Legion and reflects on the different ways the charity has supported the Armed Forces community. The Festival will also commemorate 100 years of the poppy as the symbol of remembrance. In addition, the 30th anniversary of Operation Granby, the largest deployment of U.K. Forces since World War II, will be remembered. The program will pay tribute to members of the Armed Forces who were deployed to Afghanistan as part of 2021's Operation Pitting.