WordNet sense 1 (a disagreement or argument about something important):

difference, dispute, difference of opinion

WordNet sense 2 (go against, as of rules and laws):

contravene, infringe, run afoul

WordNet sense 3 (an open clash between two opposing groups (or individuals)):

battle, struggle

WordNet sense 4 (a hostile meeting of opposing military forces in the course of a war):

engagement, fight