At the close of the Civil War, some 4 million slaves became free. But almost immediately after hostilities ceased, leaders in the ex-Confederate states began to impose a series of laws, the Black Codes, that re-instituted slavery in all but name. Just as swiftly, a wave of terrorist violence swept across the South, targeting blacks seeking education, economic independence, and a voice in civic and political life—and also whites with Union sympathies. In Washington, D.C., Republican leaders grappled with another problem: When the Southern states rejoined the Union, they would do so with more political power than they'd enjoyed prior to secession—the consequence of each African-American now counting as five-fifths, rather than three-fifths, of a person.