Other than Gettysburg or Vicksburg,make an argument for the single event you deem the most significant to the legacy of the American Civil War on

Other than Gettysburg or Vicksburg,make an argument for the single event you deem the most significant to the legacy of the American Civil War on reforms that are present in today's American Society, and explain your choice. You may choose from political, military, economics, or social impact. Your choice should include, setting, timeline, major figures,catalysts, outcomes, and statistics (if a battle). More than just a recap, this needs to explain why this is still significant today and use evidence from the past to talk about the present.