croismare was descended from an old noble family of normandy, well established at the royal court, the son of françois-nicolas, lord of botoirs and la plesse, and elizabeth de croismare, heir to the branch of the lords of la pinelière and lasson, a descendant of nicolas croixmare. in his youth, the marquis served as a captain in the infantry regiment of the king, where his brother louis-eugene has long been lieutenant-colonel. uninterested in securing the higher ranks, he left the service after receiving the cross of st. louis.