French soldiers goofing around before heading for the front, August 1914.

French soldiers goofing around before heading for the front, August 1914.

The French soldier on the left died under 72 hours later on his first day of battle near Mulhouse, Alsace, aged 24. Colourised by u/tittyswan on Reddit.

On August 7, 1914, the Battle of the Frontiers began, one of the earliest yet bloodiest campaigns of the Western Front.

Following the German declaration of war on France on August 3, both nations prepared to go on the offensive, with the French deploying their Plan XVII and the Germans their Schlieffen Plan.

On August 7, 1914, the French invaded Alsace and Lorraine, the regions they had lost in 1871.

The French achieved early success and advanced, but suffered thousands of casualties, and a German push on August 20 at Sarrebourg set them back to their starting points.

On August 21, the French attacked again further north in the Battles of the Ardennes, Charleroi and on August 22 at Rossignol.

The French suffered extreme casualties due to advancing en masse across open terrain in broad daylight with minimal artillery support, wearing extremely visible dark blue and red uniforms into German machine-guns and artillery, using outdated 19th century tactics.

The French commanders believed enough "offensive spirit" could overcome any defense.

Their attacks were uncoordinated and inflexible, and the French also badly underestimated the strength of the German force in France.

The Germans suffered heavy casualties in their attacks too, also advancing in broad daylight in open fields.

Though the Germans did have better tactics and more artillery and machine-guns than the French, which enabled them to succeed and advance.

On August 23, the British engaged the Germans for the first time in the Battle of Mons in Belgium and halted the Germans for some time before being overwhelmed by sheer numbers.