Originally Posted by W. Neils, The German General Staff in the Great War: Operation Michael, Oxford, 1989
…considerable devastation and confusion. Although measures were in place to combat chlorine gas to at least some degree, any exposed flesh was harmed by this new chemical, and soldiers inevitably retreated in the face of it. The sole saving grace from the point of view of the French was the longevity of the chemical, for it hindered the Germans from making effective defences on account of having to continue wearing their chemical retardants.
The Briey Army Group was at first taken aback by the German offensive of March 5th. However, Noël Édouard, vicomte de Curières de Castelnau, proved in the end to be adequate to the challenge, marshalling his subordinate army commanders. Despite this, serious flaws were exposed in the intelligence gathering apparatus of the French Army, and Joffre’s subsequent reorganisation can be traced to this, as we shall see. The initial failure of the French Army’s intelligence operations were also reflected on the ground, although this was not to their eventual detriment.
The first German attack was to the west of Thionville, and was a devastating success. The utilisation of mustard and chlorine gas, in both canisters and – intermittently – shells thrown by artillery, led to a complete collapse along the frontage of 14th and 28th Divisions, situated respectively on the left flank of 2nd Army and the right of 3rd Army. This collapse opened a gaping hole in the centre of the Briey Army Group, and led to panicked scenes at De Castelnau’s headquarters at Etain. Happily for the French the use of multiple types of gas, although initially causing a terrible slaughter on the infantry in the front line and their supporting units, also hindered the German advance. As a result, by midday on 6th March, 17th Division of the Briey Army Group’s Reserve, had aligned itself with the survivors of 14th and 28th Divisions slightly north of Briey, and stopped the first German attack.
Nonetheless, some 18,000 French soldiers had been killed or wounded on but the first day of this defensive action. A defensive action, moreover, against an attack only ever intended as diversionary. However, by 9th March de Castelnau was sufficiently confident to report to Victor Michel that the German offensive had been blunted. But the worst was yet to come…