Coupling of slosh dynamics within a partially filled rotating Dewar of superfluid helium II with spacecraft attitude dynamics is investigated in response to the environmental disturbances. These disturbances include 1) lateral impulse, 2) gravity gradient, and 3) g-jitter forces. The purpose of this study is to investigate 1) how helium II fluid slosh dynamics driven by various cases of environmental forces coupled with spacecraft dynamics can affect the bubble deformations and their associated fluid and spacecraft mass-center fluctuations and 2) how spacecraft translational displacement, velocity, and accelerations deviating from normal spacecraft operation are induced by the coupling with slosh dynamics driven by various environmental disturbances. The numerical computation of slosh dynamics is based on the rotating frame, whereas the spacecraft dynamics is associated with the nonrotating frame. The results show that major contributions to the orbital dynamics are driven by the coupling with slosh dynamics. Not considering the effect of slosh dynamics acting on the spacecraft may lead to the wrong results for the development of orbital and attitude control techniques.