The victory of the Union forces during the American Civil War, buoyed by nearly 200,000 Black soldiers and sailors, changed American politics forever. The abolition of slavery after the ratification of the Thirteenth Amendment to the US Constitution in 1865 ensured the freedom of approximately four million Black men, women and children, mostly in the Southern States. Citizenship for those formerly enslaved was guaranteed by the Fourteenth Amendment in 1868. Two years later the Fifteenth Amendment forbade the federal government and the various states from preventing adult men from voting in elections "on account of race, color, or previous condition of servitude." These new rights were safeguarded by the presence of federal troops in the South for about a decade after the end of the war. Half a million Black voters went to the polls in various elections during the 1870s. Approximately two thousand Black men were elected to various political offices during Reconstruction, including more than three hundred Black lawmakers in Congress and various statehouses in 1872 alone.z