The Collaborative International Dictionary of English v.0.48:

Behalf \Be*half"\, n. [OE. on-behalve in the name of, bihalven
   by the side of, fr. AS. healf half, also side, part: akin to
   G. halb half, halber on account of. See Be-, and Half,
   n.]
   Advantage; favor; stead; benefit; interest; profit; support;
   defense; vindication.
   [1913 Webster]

         In behalf of his mistress's beauty.      --Sir P.
                                                  Sidney.
   [1913 Webster]

         Against whom he had contracted some prejudice in behalf
         of his nation.                           --Clarendon.
   [1913 Webster]

   In behalf of, in the interest of.

   On behalf of, on account of; on the part of.
      [1913 Webster]