Tens of thousands of Australians and New Zealanders have attended dawn services to mark ANZAC Day.
In the Australian capital, Canberra, about 55,000 gathered at the National War Memorial to commemorate the 101st anniversary of the landings of Australian and New Zealand soldiers at Gallipoli.
Services and parades have also been held in numerous centres across both countries.
ANZAC stands for the combined forces of Australians and New Zealanders (Australian and NZ Army Corps) who fought on the Turkish peninsula during World War I.
'A tragic legacy of armed conflict'. Tens of thousands turn out for ANZAC Day services in Australia and NZ https://t.co/3FAtBtH9qu'— Seamus Kearney (@seamuskearney_) April 25, 2016
In 1915 Australian and New Zealand soldiers formed part of an Allied expedition that set out to capture the Gallipoli Peninsula to open the way to the Black Sea for the Allied navies.
The objective was to capture Constantinople, the capital of the Ottoman Empire, which was an ally of Germany during the war.
But the war turned into a stalemate, and the campaign dragged on for eight months.
At the end of 1915, the Allied forces were evacuated after both sides had suffered heavy casualties and endured great hardships.
The Allied casualties included 21,255 from the United Kingdom, of which were some 4000 Irish soldiers from the Royal Irish Fusiliers, an estimated 10,000 dead soldiers from France, 8,709 from Australia, 2,721 from New Zealand and 1,358 from British India.
News of the landing at Gallipoli made a profound impact on Australians and New Zealanders at home and April 25 quickly became the day on which they remembered the sacrifice of those who had died in the war.