Earlier she placed a wreath at a memorial in Whitehall marking when Australian and New Zealand Army Corps – shortened to Anzac - fought in the Battle of Gallipoli in 1915, News.az reports, citing BBC.

The ring of poppies with white flowers depicting the feathers of the Prince of Wales' crest had a note signed by Catherine and Prince William that paid tribute to "soldiers who made the ultimate sacrifice for our freedom".

Princess Anne attended a dawn service where she laid a wreath against Wellington Arch during a memorial service that included a reading of the John McCrae poem In Flanders Fields.PA Media

The Gallipoli campaign, part of a British-led effort to defeat the Ottoman Empire, aimed to secure a naval route through the Dardanelles from the Mediterranean Sea to Constantinople, now Istanbul, in Turkey. More than 100,000 troops died in the failed campaign that lasted into 1916.

At the Whitehall service, Reverend Dr Lyndon Drake recited from The Fallen by poet Laurence Binyon before a Royal Marines Portsmouth Road Band trumpeter played the last post after which there was a one-minute silence.

The high commissioners for New Zealand and Australia, Hamish Cooper and Jay Weatherill, walked in tandem to lay their own wreaths.

Princess Catherine joined other attendees in singing the hymn O God Our Help in Ages Past before men and women in military uniforms marched off Whitehall to the commemoration and thanksgiving service at nearby Westminster Abbey.

After that service, Catherine spoke with some of the military families.PA Media

Earlier Princess Anne attended a dawn service at Wellington Arch in London which was organised by the New Zealand and Australian high commissions.

She laid a wreath during a service that concluded with the national anthems of the United Kingdom, New Zealand and Australia.

Commemoration services were also held across New Zealand, Australia and on the Gallipoli peninsula in Turkey on Saturday morning.RoyalFamily/X

The day was also marked in Villers-Bretonneux, a village in the Somme region of France, which Australian units helped defend during World War One.