N = 2 moduli spaces and N = 1 dualities for SO(nc
) and USp(2nc
We determine the exact global structure of the moduli space of N = 2 supersymmetric SO(n) and USp(2n) gauge theories with matter hypermultiplets in the fundamental representations, using the non-renormalization theorem for the Higgs branches and the exact solutions for the Coulomb branches. By adding an (N = 2)-breaking mass term for the adjoint chiral field and varying the mass, the N = 2 theories can be made to flow to either an "electric" N = 1 supersymmetric QCD or its N = 1 dual "magnetic" version. We thus obtain a derivation of the N = 1 dualities of Seiberg.