The effects of electric fields on the temperature dependence of optical Bragg reflections in the SmC* phase of two chemically similar antiferroelectric liquid crystal were measured. These Bragg peaks are strong functions of temperature and applied fields resulted in Bragg peaks of reduced intensity and shifts to longer wavelengths. Relatively weak applied fields destroyed the Bragg peaks in both samples. The exact value of this applied field is strongly influenced by the magnitude of the dipole moment in each case.