Lincoln's Reconstruction plan was relatively lenient towards southern states, requiring them to abolish slavery and repudiate secession to regain representation. His assassination led to Andrew Johnson implementing a more permissive plan that failed to protect freedmen's rights, instead pardoning Confederates and allowing southern states to impose Black Codes restricting freedmen's activities. Congress passed laws over Johnson's veto to establish the Freedmen's Bureau and prohibit Black Codes, then impeached Johnson for violating the Tenure of Office Act.