The Collaborative International Dictionary of English v.0.48:

Bottleholder \Bot"tle*hold`er\, n.
   1. One who attends a pugilist in a prize fight; -- so called
      from the bottle of water of which he has charge.
      [1913 Webster]

   2. One who assists or supports another in a contest; an
      abettor; a backer. [Colloq.]
      [1913 Webster]

            Lord Palmerston considered himself the bottleholder
            of oppressed states.                  --The London
                                                  Times.
      [1913 Webster]