though the wars Hostile_encounter were initially localised conflicts Hostile_encounter triggered Causation by tensions over disputed Quarreling land purchases Commerce_buy , they escalated Cause_change_of_position_on_a_scale dramatically from 1860 as the government became Becoming convinced Coming_to_believe it was facing Confronting_problem united UNK resistance to further land sales and a refusal to acknowledge Judgment_communication crown sovereignty .