On Frimaire 19 Year II (December 9, 1793) she married the stationer Charles-Marie Auzou.
At the battle of Nuremberg, 27 Frimaire year IX, he led at the head of his battalion of 400 men, against a column of 4,000 Austrians, taking a large number of prisoners.
It was also by his advice that the commander in chief, Jean-Baptiste Jourdan, discovered Josias, Prince of Coburg's unfortunate position behind the Wattignies forest, compelled him to retreat across the Sambre and subsequently lifted the siege of Maubeuge: Ernouf's part in this action, the Battle of Hondschoote, earned him his promotion to Major General on 23 frimaire an II (13 December 1793).
The Law of Frimaire was passed on 4 December 1793, during the French Revolution, in which power became centralized and consolidated under the Committee of Public Safety.
He was affected to the Army of the Rhine on 26 frimaire an VIII (17 December 1799), where he distinguished himself at Fribourg and Biberach an der Riß.