WordNet sense 1 (a person who takes part in an armed rebellion against the constituted authority (especially in the hope of improving conditions)):

insurrectionist, rebel, rebel, freedom fighter

WordNet sense 2 (a member of an irregular armed force that fights a stronger force by sabotage and harassment):

guerilla, guerrilla, irregular

WordNet sense 3 (in opposition to a civil authority or government):

seditious, subversive

WordNet sense 4 (deserting your allegiance or duty to leader or cause or principle):

disloyal