The French and German presidents have commemorated the 100th anniversary of Germany’s declaration of war on France on 3 August 1914.
Francois Hollande and his German counterpart, Joachim Gauck, made a joint tribute in Alsace to soldiers killed during World War One.
They were to lay the first stone for a memorial at Vieil Armand cemetery.
On Monday, events will be held in Belgium to mark the UK’s declaration of war on Germany.
UK Prime Minister David Cameron will take part in that ceremony in recognition of the day that the UK went to war.
Some 30,000 men were killed in the mountains around Vieil Armand, known in German as Hartmannswillerkopf.
The cemetery there contains the remains of 12,000 unidentified soldiers.
Mr Hollande and Mr Gauck paid tribute to the sacrifice those men made and celebrated the importance of the modern Franco-German relationship in Europe.
