An undated archive picture shows French soldiers moving a 95 mm cannon, on the rear guard near the front, at an unknown location in France. A Viscount in the Armoured Cavalry Branch of the French Army left behind a collection of hundreds of glass plates taken during World War One (WWI) that have never before been published. The images, by an unknown photographer, show the daily life of soldiers in the trenches, destruction of towns and military leaders. The year 2014 marks the 100th anniversary of the start of WWI. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows German soldiers (rear) offering to surrender to French troops, seen from a listening post in a trench at Massiges, northeastern France. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows soldiers and horses amid a destroyed spot on the battlefield at Maurepas on the Somme front, northern France October 1916. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows French soldiers firing a 155 mm mortar from a trench on the front line, at an unknown location in France. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows a French soldier aiming an anti-aircraft machine gun from a trench at Perthes les Hurlus, eastern France. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows French soldiers standing in German trenches seized after being shelled on the Somme front, northern France in 1916. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows a French officer standing near a cemetery with recent graves of soldiers killed on the front lines of World War One (WWI), at Saint-Jean-sur-Tourbe on the Champagne front, eastern France December 19, 1916. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows French artillery officers on the phone relaying instructions to adjust cannon fire in a trench on the front line, at an unknown location in France. (Photo by Collection Odette Carrez/Reuters)

An archive picture taken shows a statue of Christ on the cross on a tree at Fricourt on the Somme front in France October 1916. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows a French soldier in a sap trench just after being shelled at Mont Tetu near Massiges, eastern France. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows French troops in trenches above Ablain-Saint-Nazaire in the Artois front, northern France, in 1916. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows French officers inspecting trenches on the Argonne front, eastern France May 1916. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows a shelter for machine gunners in a French trench at Apremont-la-Foret, eastern France. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows French General Joseph Joffre (2nd R) congratulating and awarding medals to soldiers, who fought in the Battle of Verdun, in Verdun March 1916. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows Field Marshal Horatio Herbert Kitchener (2nd L) meeting French General Albert Baratier (R), on horseback, as French Marshal Joseph Joffre looks on (2nd R), on the Champagne front, Eastern France in 1915. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows Field Marshall Douglas Haig riding a horse at an unknown location in France February 14, 1916. Haig was the British commander-in-chief during the Somme battle. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows French General Emile Eugene Belin (R) visiting the front line near Arras, Northern France. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows French soldiers posing in a trench at Suippes on the Champagne front, eastern France. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows French cyclists of the Cavalry Corps, on the Champagne Front, Eastern France September 22, 1915. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows a dog pulling a Belgian machine gun at an unknown location in northern France. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows carcasses of animals strung up before being cooked for soldiers, on the Champagne front, eastern France. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows French soldiers posing outside their shack, called “The Chalet”, at la Sapiniere near Lachalade on the Argonne front, eastern France. (Photo by Collection Odette Carrez/Reuters)

An archive picture taken shows soldiers attending an entertainment show at Suippes, on the Champagne Front, Eastern France in 1915. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows French troops from the rear guard eating lunch near Arras, Northern France. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows captured Germans soldiers marching through Chalons en Champagne, Eastern France September 1915. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows a French soldier after taking a shower, at the rear guard near the front line, at an unknown location in France. The placard reads “Thermal complex of the Poilu, showers, massages, chiropodist, manicurist. Free massages for women”. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows a priest conducting mass for French soldiers on the Champagne front, eastern France in 1915. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows injured soldiers arriving at a hospital before being evacuated on the Champagne front, eastern France. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows soldiers attending an entertainment show at Suippes, on the Champagne Front, Eastern France in 1915. (Photo by Collection Odette Carrez/Reuters)

An archive picture shows soldiers at a train for injured soldiers in Calais, Northern France in 1915. (Photo by Collection Odette Carrez/Reuters)

An undated archive picture shows Germans soldiers, captured during the Battle of Verdun, taking off their clothes for a body search by French soldiers, in Eastern France. (Photo by Collection Odette Carrez/Reuters)