The Collaborative International Dictionary of English v.0.48:

Militancy \Mil"i*tan*cy\, n. [See Militant.]
   [1913 Webster]
   1. The state of being militant; warfare.
      [1913 Webster]

   2. A military spirit or system; militarism. --H. Spencer.
      [1913 Webster]

WordNet (r) 3.0 (2006):

militancy
    n 1: a militant aggressiveness [syn: combativeness,
         militance, militancy]

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "militancy":
   action, activeness, activism, activity, aggression, aggressiveness,
   antagonism, bellicism, bellicosity, belligerence, belligerency,
   business, chauvinism, combativeness, contentiousness, doings,
   fight, goings-on, hostility, jingoism, martialism, militarism,
   motion, movement, political activism, proceedings, pugnaciousness,
   pugnacity, quarrelsomeness, saber rattling, stir, truculence,
   unfriendliness, unpeacefulness, warmongering, warpath