Duchess Meghan, Prince Harry join queen for Royal Air Force 100th anniversary celebrations

A clutch of royals, led by Queen Elizabeth II and joined by Prince Harry and his new wife, Duchess Meghan of Sussex, led celebrations Tuesday marking the 100th anniversary of the founding of the Royal Air Force. 

A day crowded with royal ceremony began with a special service in Westminster Abbey, to be followed by a parade in The Mall and a traditional spectacular flypast over Buckingham Palace where Queen Elizabeth II and other royals were scheduled to watch from the famous palace balcony.

The new Duke and Duchess of Sussex were to join her at some of the ceremonies, along with Prince William, Prince Charles and his wife, Duchess Camilla of Cornwall, Princess Anne the Princess Royal, Prince Andrew and Prince Edward and their wives. 

For the Abbey service, Meghan wore a black Dior dress with a boatneck neckline and a matching Stephen Jones fascinator. She paired the look with nude heels and a clutch.

Duchess Kate of Cambridge also made an appearance, a day after she appeared at the Chapel Royal in St. James's Palace for the christening of her third baby, Prince Louis of Cambridge, who was born April 23. 

Kate opted for a mint Alexander McQueen coat dress with a matching hat by Sean Barrett as well as a diamond and ruby Darce brooch, a high honor from the Air Cadets.

Missing was the queen's husband, Prince Philip, 97, who has retired from public life

Harry, 33, a former captain in the British Army, and Meghan, 36, were to cheer the RAF just hours before they were scheduled to depart Tuesday evening for Dublin, Ireland, for a 24-hour visit jam-packed with engagements, including an eagerly anticipated walkabout at Trinity College's Parliament Square on Wednesday.

The official Sussex itinerary in Ireland includes parties, sports, meetings with Irish Prime Minister Leo Varadkar and President Michael Higgins, and visits to see the historic Book of Kells in Trinity College's famed Old Library, to pay respects at the nearby memorial to the Irish Famine and to explore the Irish Emigration Museum.

The queen, 92, was to be front and center for the RAF events. Besides the Abbey service and the flypast, she was scheduled to take the Royal Salute, present a new Queen's Colour to the RAF at a ceremony on the forecourt of Buckingham Palace, and then make a brief speech. 

After a busy week in Scotland last week, the queen faced another busy week ahead in London, including a meeting with visiting President Donald Trump and first lady Melania Trump on Friday. She was unable to attend the christening of Prince Louis of Cambridge on Monday, as she was traveling, but paying homage to Britain's military services is one of her most important roles as monarch. 

The RAF, described as the world's first independent air force, was founded on  April 1, 1918 as an armed force independent of the British Army and the Royal Navy. It played a key role in defending the skies of Britain during WWII, when the queen was still a teen and her father, King George VI, was on the throne. 

A century later, the RAF is engaged in 13 missions across 26 countries and is heavily committed on operations both at home and abroad, according to Buckingham Palace.