Which civil rights tactic was most directly responsible for african americans' gaining equal access to the ballot box, especially in southern states, during the 20th century?

Why was "impressment" an important issue during the jefferson administration? the united states was being treated disrespectfully, as the spanish navy was forcing american sailors into naval service for them. the united states was being treated disrespectfully, as the french navy was forcing american sailors into naval service for them. the united states was treating british navy with disrespect by forcing british sailors into naval service for them. the united states was being treated with disrespect on the high seas, as the british navy was forcing american sailors off their ships and into naval service for them. the united states was treating french navy with disrespect by forcing french sailors into naval service for them.