WordNet (r) 3.0 (2006):

battle cry
    n 1: a yell intended to rally a group of soldiers in battle
         [syn: war cry, war whoop, rallying cry, battle cry]
    2: a slogan used to rally support for a cause; "a cry to arms";
       "our watchword will be `democracy'" [syn: war cry,
       rallying cry, battle cry, cry, watchword]

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "battle cry":
   Angelus, Angelus bell, alarm, alarum, bark, bawl, bellow,
   bid to combat, birdcall, bugle call, call, call to arms, call-up,
   catchword, caterwaul, challenge, cheer, clarion, clarion call,
   conscription, cry, dare, defi, defy, double dare, exhortation,
   gage, gage of battle, gauntlet, glove, go for broke, gung ho,
   halloo, holler, hollo, hoot, howl, hurrah, last post, levy,
   mobilization, moose call, motto, muster, rally, rallying cry,
   rebel yell, recruitment, reveille, roar, scream, screech, shout,
   shriek, slogan, squall, squeal, summons, taps, trumpet call,
   war cry, war whoop, watchword, whistle, whoop, yammer, yap, yawl,
   yawp, yell, yelp, yo-ho, yowl