The Collaborative International Dictionary of English v.0.48:

Brandenburg \Bran"den*burg\, n. [So named after Brandenburg, a
   province and a town of Prussia.]
   A kind of decoration for the breast of a coat, sometimes only
   a frog with a loop, but in some military uniforms enlarged
   into a broad horizontal stripe.
   [1913 Webster]

         He wore a coat . . . trimmed with Brandenburgs.
                                                  --Smollett.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

Brandenburg
    n 1: the territory of an Elector (of the Holy Roman Empire) that
         expanded to become the kingdom of Prussia in 1701