King Charles, William and Kate attend first Commonwealth Day since queen's death: See photos

As King Charles III's coronation soon approaches, the British monarch is celebrating his first Commonwealth Day as the sovereign.

Charles, 74, was joined by family, including wife Queen Consort Camilla, son Prince William, daughter-in-law Princess Kate and his siblings Prince Edward and Princess Anne for Commonwealth Day service at Westminster Abbey Monday.

The royal family was greeted outside by a Maori group before heading inside for the service.

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William and Kate's appearance was their first Commonwealth Day as the Prince and Princess of Wales. The couple matched each other in navy ensembles. Kate paid tribute to Williams' parents, wearing a pair of sapphire and diamond earrings, previously worn by Princess Diana, and the Prince of Wales feathers brooch, a gift from Charles. Charles was the Prince of Wales before ascending to the throne.

Kate tried her best to hold her hat to her head during a windy day at Westminster. Her peplum jacket and skirt with white embroidery were also tousled in the wind.

William opted for a simpler outfit in a navy suit with a blue tie.

In a speech to mark the occasion, Charles referenced his "beloved mother" Queen Elizabeth II, who died in September. "In succeeding Her Majesty as Head of the Commonwealth, I draw great strength from her example, together with all that I have learnt from the extraordinary people I have met, throughout the Commonwealth, over so many years," he said.

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The monarch also spoke about his hopes for the future of the Commonwealth amid the Charter of the Commonwealth's tenth anniversary, centering "peace and justice; tolerance, respect and solidarity; care for our environment, and for the most vulnerable among us."

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"These are not simply ideals. In each lies an imperative to act, and to make a practical difference in the lives of the 2.6 billion people who call the Commonwealth home," he added.

With the Commonwealth ruling over a third of the world's population, Charles said he hopes to tackle issues on "climate change and biodiversity loss, youth opportunity and education, global health, or economic cooperation" with a collaborative effort from fellow countries.

"The Commonwealth has an incredible opportunity, and responsibility, to create a genuinely durable future – one that offers the kind of prosperity that is in harmony with Nature and that will also secure our unique and only planet for generations to come," he said in the impassioned speech. "Let ours be a Commonwealth that not only stands together, but strives together, in restless and practical pursuit of the global common good."

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This article originally appeared on USA TODAY: King Charles III, William and Kate join for Commonwealth Day