The American Civil War tore apart and tested a young nation not yet 100 years old. The era surrounding the war saw the end of slavery and the passage of the 13th, 14th, and 15th Amendments, important revisions to the U.S. Constitution. The period immediately following the Civil War provides opportunities to study how shared values of white Northerners and Southerners limited the potential for establishing a truly biracial democracy, and the persistence of racial tensions that would help define the 20th century.