Meghan Markle made her first public appearance on Saturday since giving birth to her son, Archie Harrison Mountbatten-Windsor. The Duchess of Sussex attended the traditional Trooping the Colour with Prince Harry. The event is an official celebration of the Queen's birthday.

Onlookers got their first glimpse of the royal couple as they exited Buckingham Palace in a horse-drawn carriage with Kate Middleton, the Duchess of Cambridge, and Camilla, the Duchess of Cornwall. Thousands of people gathered along the Mall in London to watch the spectacle, which featured more than 200 horses, 400 musicians and 1,400 officers.

Aside from the appearance when the new parents introduced Prince Archie to the world, the Duchess has remained out of the public eye. She was all smiles during the event, wearing a navy Givenchy outfit by her wedding dress designer, Clare Waight Keller, and a matching navy hat by Noel Stewart.

Meghan, Duchess of Sussex and Prince Harry, Duke of Sussex arrive at Trooping The Colour, the Queen's annual birthday parade. Chris Jackson / Getty Images

Trooping the Color is a ceremony deeply rooted in the history of the United Kingdom. It originated from traditional preparations for battle when flags, or colors, were "trooped" so soldiers in the ranks would be able to recognize them. The parade allows Queen Elizabeth II to review her army, as she is technically the head of Britain's armed forces.

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The Queen, who is the longest living monarch, turned 93 in April. Prince Philip, the Duke of Edinburgh, who celebrates his 98th birthday on Monday, has retired from official public duties and did not attend the event.

The royal colonels — the Prince of Wales, Colonel of the Welsh Guards, Princess Royal, Colonel of the Blues and Royals, the Duke of Cambridge, Colonel of the Irish Guards and the Duke of York, Colonel of the Grenadier Guards — all rode on horseback as part of the parade, according to the BBC.

Extended members of the royal family stood on the palace's front balcony to watch the Royal Air Force fly by.

Members of the Royal Family on the balcony of Buckingham Palace to watch a fly-past of aircraft by the Royal Air Force during Trooping The Colour. Chris Jackson / Getty

Theresa May, who formally stepped down as prime minister Friday, but will remain in office until a successor has been appointed, was also in attendance.

Meghan appeared happy and healthy when she and Harry introduced baby Archie to the world in May. At the time, she said her son had "been a dream" and has the "sweetest temperament, he's really calm." The new-born slept right through his first media encounter.

"It's magic, it's pretty amazing, and I have the two best guys in the world, so I'm really happy," she said during her son's first brief encounter with a TV camera.