Are you looking for Repin, Repnin or Repnin-Volkonski? What did he do?

Is this the Essen you seek? If not, what did he do?:

Эссен-2, Александр Александрович (ум. в 1805), генерал-лейтенант, шеф Черниговского драгунского полка.

Essen-2, Aleksandr Aleksandrovich (deceased 1805), general-lt, shef Chernigorsk dragun polk.