When the Battle of Verdun broke out, Colonel Estienne was in charge of the artillery of the 3rd Army Corps. On August 6, 1916, he was once again cited in the 2nd Army order:
"Acting commander of the artillery of the 3rd Army Corps: senior officer of the highest value. As commander of the artillery of one of the most important groups, he rendered the most eminent services in the fighting at Verdun from the beginning of April until the middle of June. Thanks to his technical competence combined with an uncommon flexibility of intelligence and tireless activity, Colonel Estienne was able, in a sector of continuous fighting, to fulfill a particularly difficult mission. Two days later, he was promoted to the rank of brigadier general.
General Estienne is appointed Director of the Special Artillery
After the fighting in Verdun, Estienne was placed at the disposal of the Ministry of War to set up tank units and to direct the training of its personnel. He then set up the Trou d'Enfer center in Marly-le-Roi and the Cercottes center and became commander of the Assault Artillery. After the first uncertain engagements, the tanks quickly won their place on the battlefields. On August 9, 1918, Estienne was made Commander of the Legion of Honor. The weapon he helped develop played a decisive role in the final Allied victory.