Prince William, British Prime Minister Theresa May, Australian Veterans' Affairs Minister Darren Chester and former German president Joachim Gauck were among the dignitaries who marked the centenary of a critical World War I battle in northern France.
They were joined by the relatives of soldiers who served and died in the conflict at the commemorative service held on Tuesday in Amiens Cathedral in northern France. Mr Chester laid a wreath in the Chapel of the Allies.
About 9000 Allied troops, including 2000 Australians, launched the Battle of Amiens on August 8, 1918. The battle changed the course of the war, as the comprehensive Allied victory finally convinced German commanders they could not win. Diggers played a leading role in the battle.
William acknowledged the debt owed to the First World War troops in a message printed in the official programme: "The Battle of Amiens, and the continued fighting which followed during the summer of 1918, brought the Allies hope and optimism after four long years of bloodshed and stalemate."
At the service, the story of the battle was told through contemporary letters, diaries and poems read by guests from the 2000-strong congregation.
"What began here on August 8 was truly a coalition operation under the strategic command of a great Frenchman, Marshal Foch, a battle in which the forces of many nations came together to fight; in which aerial, mechanical and human courage and ingenuity combined with devastating results," William said.
"Amiens was symbolic of the Entente Cordiale, the co-operation without which victory was impossible.
"It is entirely fitting therefore, that today, that same international coalition has returned to Amiens with our former enemy in peace and partnership."
General Sir Henry Rawlinson, commander of the Fourth Army, combined air and land forces from Australia, Canada, France, America and Britain to great effect during the battle.
He had learnt the lessons of the bloody Somme offensive, employing improved tactics and new technology, utilised alongside subterfuge, from concealing troop numbers to ending the practice of firing range-finding shells so there was no warning of the attack.
The battle saw more than 500 tanks from the UK's Tank Corps deployed, more than 1900 British and French aircraft used, tens of thousands of troops present, with the Australians and Canadians prominent in the attack, and all supported by more than 2000 guns from the Royal Artillery.
Over the following days the gains made by Allied troops were significant with many miles claimed from German forces, but its real impact was on the morale of many in the German high command, convincing them the war could not be won.
During this phase of the war, the Australians fought in a series of battles, most famously at Mont St Quentin and Peronne before fighting their last infantry battle on the Western Front at Montbrehain on October 5, 1918.
"As the Anzac Centenary 2014-18 comes to a close it is important to remember these critical battles at the end of the First World War," Mr Chester said.