  We present brane constructions in Type IIA string theory for N=1
supersymmetric SO and Sp gauge theories with tensor representations using an
orientifold 6-plane. One limit of these set-ups corresponds to N=2 theories
previously constructed by Landsteiner and Lopez, while a different limit yields
N=1 SO or Sp theories with a massless tensor and no superpotential. For the
Sp-type orientifold projection comparison with the field theory moduli space
leads us to postulate two new rules governing the stability of configurations
of D-branes intersecting the orientifold. Lifting one of our configurations to
M-theory by finding the corresponding curves, we re-derive the N=1 dualities
for SO and Sp groups using semi-infinite D4 branes.
