VERDUN, France -- France's president and Germany's chancellor want their countries' improbable friendship to be a source of hope for today's fractured Europe as they commemorate the centenary of the longest battle of World War I.

In extensive ceremonies Sunday in eastern France, Francois Hollande of France and Angela Merkel of Germany are marking 100 years since the 10-month Battle of Verdun, which killed 163,000 French and 143,000 German soldiers and wounded hundreds of thousands of others.

With no survivors left to remember the war, the commemoration events are focusing on educating youth, and will include 4,000 French and German children.

Merkel said Saturday the event shows how good German-French relations are today and the achievements of European unity. She expressed hope Britain would not vote to leave the European Union next month.