Prime Minister Malcolm Turnbull has praised the feats of Australian troops in the battle to re-take the French village of Villers-Bretonneux exactly a century ago.
Mr Turnbull was speaking at the dawn service at the war cemetery at Villers-Bretonneux in northern France, with dignitaries including Britain Prince Charles among the thousands of people attending.
The Prime Minister said the actions of Australian troops who blunted the German army's Spring Offensive helped pave the way for the eventual Allied victory on the Western Front.
"The Australians were called upon just three years on from the landing on Gallipoli. It was said they had no chance — but they were confident. In classic Australian style. 'Boys, you know what you have to do — get on with it'."
Villers-Bretonneux is now home to the main Australian Memorial on the Western Front.
Earlier Mr Turnbull and French Prime Minister Edouard Philippe opened the Sir John Monash Centre museum, is named after the Australian general responsible for taking the town.
Mr Turnbull and his wife Lucy also visited the grave of her great-uncle Roger Hughes who was killed by a German shell in 1916, five days after arriving on the Western Front as a 26-year-old military doctor.
In Turkey, crowds gathered early for the service at Anzac Cove at Gallipoli, where the Australian and New Zealand troops landed under British command in 1915 in an ill-fated attempt to take the Ottoman Empire out of the war.
Home Affairs Minister Peter Dutton represented Australia at a ceremony that brought together Turkish, New Zealand and Australian troops.
"It is the greatest honour for all of us to gather here at North Beach as dawn breaks more than a century after this campaign was fought," Mr Dutton said.
"It is humbling to stand among our New Zealand and Turkish friends and reflect on the service and sacrifice of the tens of thousands of people on both sides of the campaign who lost their lives."
More than 44,000 Allied soldiers were killed at Gallipoli, Turkish casualties were estimated at 250,000.
In London, Prince Harry and his bride-to-be Meghan Markle attended an Anzac Day service at Wellington Arch before laying a wreath at the Australian memorial.