  A residual gauge symmetry, exhibited by light-front gauge theories quantized
in a finite volume, is analyzed at the quantum level. Unitary operators, which
implement the symmetry, transform the trivial Fock vacuum into an infinite set
of degenerate coherent-state vacua. A fermionic component of the vacuum emerges
naturally without the need to introduce a Dirac sea. The vacuum degeneracy
along with the derivation of the theta-vacuum is discussed within the massive
Schwinger model. A possible generalization of the approach to more realistic
gauge theories is suggested.
