Source : Webster's Revised Unabridged Dictionary (1913)

Combativeness \Com"bat*ive*ness\, n.
   1. The quality of being combative; propensity to contend or
      to quarrel.

   2. (Phren.) A cranial development supposed to indicate a
      combative disposition.

Source : WordNet®

combativeness
     n : a militant aggressiveness [syn: {militance}, {militancy}]