We study the dynamics of a Morse oscillator subjected to periodic impulsive forcing. The system is governed by an area-preserving map that is factored explicitly into the product of two orientation-reversing involutions. The symmetry lines of these involutions are determined analytically. We discuss the organization of periodic and homoclinic orbits by symmetry and classify each according to the symmetry lines it visits. Finally, we generalize some of our findings to a larger class of impulsively driven Hamiltonian systems.