French and German leaders mark WW1 anniversary
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.'Example for world'
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.
"The history between France and Germany proves that good will can triumph over fatality, and that the people who considered themselves as hereditary enemies, can over a few years, reconcile their differences" Mr Hollande said.
Mr Hollande added that the friendship between the two countries was "an example for the world, a strength and an invitation, wherever peace is threatened, wherever human rights are violated, wherever the principles of international law are flouted".
He also called on the international community to push for a ceasefire in Gaza in order to "end the suffering of civilian populations".
They were to lay the foundation stone for a Great War memorial and exhibition centre on the site, which is due to open its doors to the public in 2017.
The two leaders will meet again on Monday in the Belgian city of Liege, where heads of state from across Europe will mark the escalation of the war after Germany invaded Belgium.