I don’t think the French Army ever executed one in ten men as a “stiffener”.
Verdun was 1916. The widespread mutinies in the French Army were in 1917 following General Nivelle’s disastrous major attack on the Germans, along the River Aisne.
Ironically Nivelle, who was quite a charismatic leader, had made his name at Verdun, driving back part of the German Army.
Verdun was entirely a French battle, initiated by the Germans who intended, in the words of their commander “to bleed the French Army white on the anvil of Verdun”.
A truly horrible battle which probably resulted in a million casualties in total.
The British attack on the Somme in July 1916 certainly relieved pressure on the French at Verdun, but the Somme offensive was planned originally by the joint French and British High Commands in 1915, and was intended originally to be a major French attack with British support.
Verdun changed all that, and the British found themselves launching a major assault over ground not of their choosing, with French support on their Southern flank.
Another million casualties.
These two terrible battles in 1916, “the year of killing” (John Terraine), did at least serve to break the German Army on the Western Front.
Little wonder that people at home might name their new born children after these events, which were cataclysmic even by WW 1 standards.