Union troops in the South had been used to manipulate the vo…

Union troops in the South had been used to manipulate the vote in order to get this individual elected president.  Union troops in the South had been used to manipulate the vote in order to get this individual elected president. After this election, it was determined that the African American vote could decide an election.   As a result of this which of the following gave African American men the right to vote all over the U.S.?