A car is parked near the former Episcopal Palace on March 11, 2014 in Verdun, France. Inset: A French soldier in the ruins of Verdun after a German bombing In 1916. (Photo by Peter Macdiarmid/Getty Images)

People walk near Reims Cathedral on March 11, 2014 in Reims, France. Inset: Reims Cathedral during a bombardment, April 30, 1914. The centennial anniversary of the start of WWI is on July 14, 2014. (Photo by Peter Macdiarmid/Getty Images)

Cars are parked near Les Halles in the Grote Markt on March 10, 2014 in Ypres, Belgium. Inset: Les Halles in the Belgium town of Ypres, the site of three major battles during World War I, and almost completely devastated by bombing, 1915. (Photo by Peter Macdiarmid/Getty Images)

Cars are parked near Place de la Concorde on March 12, 2014 in Paris, France. Inset: World War I, German airplanes at Place de la Concorde in Paris, wrecked by celebrating crowds on the day of the restoration of Alsace-Lorraine, November 18, 1918. (Photo by Peter Macdiarmid/Getty Images)

A man stands near Vareddes town hall on March 12, 2014 in Vareddes, France. Inset: German troops, taking a rest during the First Battle of the Marne, sit on the steps of the Vareddes Town Hall, France, 1914. (Photo by Peter Macdiarmid/Getty Images)

Cars are parked at the former railway station on March 12, 2014 in Roye, France. Inset: soldiers standing outside the ruins of the railway station at Roye, Somme, France, during World War 1, 1917. (Photo by Peter Macdiarmid/Getty Images)

Trees surround the Somme canal on March 12, 2014 in Frise, France. Inset: members of a Royal Garrison Artillery working party carrying duck-boards across the frozen Somme canal at Frise, March 1917. (Photo by Peter Macdiarmid/Getty Images)

Traffic runs from Basilica of Notre-Dame de Brebieres on March 13, 2014 in Albert, France. Inset: a view of the Basilica with the statue of the Virgin tilted due to a shell, 1915. (Photo by Peter Macdiarmid/Getty Images)

People walk near Place des Heros on March 14, 2014 in Arras, France. Inset: the town hall and the belfry of Arras in ruins, seen from the main square, Pas-de-Calais. (Photo by Peter Macdiarmid/Getty Images)

People stand at Trafalgar Square on March 17, 2014 in London, England. In Trafalgar Square, London street urchins dressed as soldiers with paper hats and canes as guns stand to attention watched by a small crowd. Behind them is a notice declaring “The Need for Fighting Men is Urgent”, November, 1914. (Photo by Peter Macdiarmid/Getty Images)

A gated barrier runs near Scotland Yard on March 17, 2014 in London, England. Inset: a large crowd of men respond to a call by the War Office for married men aged between 36 and 40 to become munition workers. They gathered outside the Inquiry Office at Scotland Yard in London, England during World War I. (Photo by Peter Macdiarmid/Getty Images)