[2] He and his brother Christian Hartmann Pfeiffer were identical twins, and their birth was so stressful on their mother that it led to her death shortly thereafter.

[4] They had four children[2] In 1806, under Westphalian rule, he was made procurator fisci, and in 1810 procureur du roi (crown prosecutor) in Cassel.

[11][12] In 1814, with the return of the Electorate of Hesse, Pfeiffer was named to the High Court in Cassel and by 1817 he was appointed a Hofgerichtsrat (government councillor) and member of the Ober-Rentkammer (Council of the Treasury).

[2] Whether this was true or not, upon Wilhelm II's death, Franz was recalled to Cassel by his son and successor, Frederick William, who appointed him Ober-Zolldirector (chief customs officer) in 1847.

[3] Shortly thereafter, whether through fault of his own, or through his relation to his brother Burkhard, Pfeiffer was removed from his position by Ludwig Hassenpflug, and returned to his home in Cassel, where he lived out the remainder of his life.