The Duke of Cambridge attended the commemorations, held at Amiens Cathedral, that marked the centenary of the Battle of Amiens.
Starting on 8 August 1918, the Battle of Amiens marking a turning point in the First World War. The Allied forces, made up of British, Australian, Canadian, French and US soldiers, advanced over seven miles on the first day.
The battle heralded the Hundred Days Offensive and started the path to the Armistice in November 1918.
Around 2,000 guests attended the ceremony, which featured readings including diary extracts, letters, poems and personal accounts from those who were there.
The Duke of Cambridge gave the opening reading at the Service:
"Today we return to learn more about the experience of those involved during the historic summer of 1918, to honour the fallen of all nations, to commemorate all those who participated in this great endeavour & to celebrate the bonds of friendship which unite our nations."
His Royal Highness also laid flowers in the Chapel of Allies, alongside representatives from the partner countries, as a reaffirmation of friendship between the Allies, Germany and the city of Amiens.