Napoleon made the five brothers, first cousins and grandson of general Desaix Barons of the Empire, despite the fact that none of ranked higher than captain. He insisted however that their illustrious ancestor be remembered on the coats of arms which were granted letters patent in 1808 and 1812. The coats of arms are all quartered in the same way: in the first quarter, argent with a band of gules, charged with three shells argent, deriving from the ancient arms of the Des Aix family, but whose shells were of gold; in the second, gules, sword mounted with argent and placed in pale – this is the ‘franc-quartier’ of ‘barons militaires’, except that there the blade of the sword is sable (black) and not argent; in the fourth quarter, three golden pyramids arranged horizontally and superimposed and resting upon a terrace. The third quarter is ad libitum so as to be able to differentiate the different branches of the family. Here shown is the quarter belonging to Casimir-Marie (1801-1880) brother of the general and to Annet-Gilbert-Antoine (1772-1815) his first cousin, which is azure with two cinquefoils argent resting upon a crescent of the same. Louis-Amable (1773-1835) another brother of the general and Louis-Jean (1790-1845), his grandson, have:
argent with lion rampant on gules. Finally, Gilbert-Antoine (1761-1833), another first cousin, adopted: gules with a tower argent, supported by two batons of the same in saltire.
See the article by Marc Juillet, "Le général Desaix, ami de Bonaparte"
in the Revue du Souvenir napoléonien n°363.