Why was Oscar Romero a hero to El Salvador?

He worked to stop the killings of people by the U.S. backed death squads. He was originally a conservative, non political bishop. As the human rights abuses in El Salvador escalated, he became part of a movement to use the Church resources to save people from death squads and became an outspoken advocate for human rights. He started to challenge the unfair political and economic structure in El Salvador that was fueling the war. He was murdered while giving Good Friday Mass.