The characteristic wake states of a cylinder undergoing forced sinusoidal oscillations transverse to the free-stream are studied by simultaneously measuring the structure of the near wake and the forces on the cylinder. The wake exhibits two distinctly different wake states. The transition between these states corresponds to a large discontinuous change in the phase of both the total and vortex forces on the cylinder, as well as the mode and phase of vortex shedding. Over the range of flow and oscillation parameters studied the vortex lift and drag phases collapse towards values that depend primarily on wake state. This is in contrast with the phase of the total lift force, which varied significantly with both A/D and Re.