  We study the stringy description of N=1 supersymmetric SU(N) gauge theory on
R^{1,2}xS^1. Our description is based on the known Maldacena-Nunez solution,
properly modified to account for the compact dimension. The most interesting of
its properties is that extra BPS M-branes are present, which generate a
non-perturbative superpotential that we explicitly compute.
