Le coup de main du Mont-sans-Nom was a commando operation of the First World War conducted on July 14, 1918 by the detachment of Lieutenant Darius Balestié and in particular by the Free Corps of Sergeant Joseph Darnand. It provided important informations on artillery and maps on the impending German offensive that would later be called the "Fourth Battle of Champagne" ("Friedensturm" for the Germans) whose failure would mark a decisive victory for the Allies.
Informed since July 7 that he would be attacked at any moment, Gouraud set a second line of defence two kilometres behind his positions and sought field information by ordering the commando raid of Mont-sans-Nom. It was a success and prisoners revealed that a massive seven-day long artillery preparation with mustard gas shells was scheduled to begin at midnight ten. Half an hour before German artillery preparation, the French launched a counter-batterie fire that disabled the artillery units preparing for the assault and shook the infantry units.
Nevertheless the German assault continued, as scheduled, on July 15, 1918, at 4:45 a.m., accompanied by a rolling barrage of conventional artillery. The first French trenches were captured despite heavy machine gun fire, but three quarters of them were unoccupied, as their defenders had withdrawn as planned (Petain directive numéro 4).
The Germans attacked the main line at 08:30 the following morning, an hour after their schedule. They were stopped by accurate fire by the bulk of the French artillery. This barrage forced the German troops to take shelter in the French evacuated shelters that were allegedly trapped with mustard gas. Accompanying tanks exploded on explosive cords hidden in their paths. They tried again at noon, but failed.
Arriving in front of the intact and reinforced second positions, the assault battalions could not force the lines without the support of heavy artillery. The exploitation troops that followed the breakthrough, were decimated by artillery grapeshots.
On July 16, after a final German assault, Gouraud's troops returned to the abandoned positions. It convinced the German commanders that they could not prevail.