National Security & Defense. The Radicals’ first step was to refuse to seat any Senator or Representative from the old Confederacy. Next they passed measures dealing with the former slaves. Johnson vetoed the legislation. The Radicals mustered enough votes in Congress to pass legislation over his veto–the first time that Congress had overridden a President on an important bill. They passed the Civil Rights Act of 1866, which established Negroes as American citizens and forbade discrimination against them.