The Collaborative International Dictionary of English v.0.48:

Offensive \Of*fen"sive\, n.
   The state or posture of one who offends or makes attack;
   aggressive attitude; the act of the attacking party; --
   opposed to defensive.
   [1913 Webster]

   To take the offensive, To act on the offensive, To go on
   the offensive, to be the attacking party; to initiate
      hostilities.
      [1913 Webster +PJC]