VERDUN, France — In solemn ceremonies here Sunday, French President Francois Hollande and German Chancellor Angela Merkel marked 100 years since the Battle of Verdun, determined to show that, despite the bloodbath of World War I, their countries’ improbable friendship is now a source of hope for today’s fractured Europe.

The 10-month battle at Verdun – the longest in World War I – killed 163,000 French and 143,000 German soldiers and wounded hundreds of thousands of others.

Between February and December 1916, an estimated 60 million shells were fired and one out of four didn’t explode, making the area so dangerous that housing and farming are still forbidden. The front-line villages destroyed in the fighting were never rebuilt.

With no survivors left to remember, Sunday’s commemorations were focused on educating youth about the horrors and consequences of the war.

Amid rising support for far-right parties and divisions among European countries over how to handle refugees, Hollande said Europe’s role is “to fight against terrorism, fanaticism, radicalization” and at the same time to “welcome populations who are fleeing massacres.”

At the Douaumont Ossuary, a memorial to 130,000 unidentified French and German soldiers, Merkel said the dead of Verdun were “victims of bigotry and nationalism, of blindness and political failure,” and that the best way to commemorate them is to bear in mind “the lessons that Europe drew from the catastrophes of the 20th century – the ability and willingness to recognize how necessary it is not to seal ourselves off but to be open to each other.”

Merkel declared that “the common challenges of the 21st century can only be dealt with together.”

About 4,000 French and German children re-enacted battlefield scenes to the sound of drums amid thousands of white crosses marking the graves – falling on the ground in a moving evocation of death, and getting back up as a symbol of hope, in a ceremony conceived by German filmmaker Volker Schloendorff.