[1] Born in an aristocratic family of the Ancien Régime, Desvaux was admitted at the Artillery School of Châlons in 1792, before joining the Army of the Alps, with which he would take part to the siege of Lyon.

He becomes aide-de-camp to general Auguste de Marmont and is promoted to the rank of colonel in 1803, taking part to the siege of Ulm, where he was wounded, before being captured by the enemy at the battle of Judenburg.

Set free after the Treaty of Pressburg at the end of 1805, he spent the next year serving as commander of the French artillery in Dalmatia and then Friuli.

In 1809, he took part to the War of the Fifth Coalition and was promoted to brigadier general; after the end of the campaign in Austria, he was given the command of the prestigious Horse Artillery of the Imperial Guard.

A baron of the Empire from 1810, Desvaux held his command in the Guard and was a part of the Grande Armée during the Russian Campaign and then War of the Sixth Coalition.