African Americans were freed by the Thirteenth Amendment but gained little thereafter. The defeated Southern States were bitter and resentful and determined to keep African Americans as near slavery as possible. Most Southern States passed "Black Codes that severely restricted the rights of African Americans. Although they were guaranteed civil rights under the Fourteenth Amendment, their rights were violated with abandon. Blacks were forced to use separate facilities and denied the right to sit on juries. In fact, in 1896, the U.S. Supreme Court sanctioned the actions of Southern States in the case of Plessy vs. Ferguson in which the Court held that racially separated facilities were constitutionally protected, as long as they were "equal;" hence the doctrine of "Separate but Equal" which remained in force until 1954. Similarly, African Americans were guaranteed the right to vote under the Fifteenth Amendment; yet the Southern States developed creative ways to circumvent this Amendment, typically by imposing poll taxes, literacy requirements, etc. The Freedman's Bureau and other organizations attempted to help blacks; however, their efforts were often frustrated by groups such as the Ku Klux Klan and Knights of the White Camellia which terrorized African Americans. Ultimately, those who came to help