Coupling of slosh dynamics within a partially filled rotating Dewar of superfluid helium II with spacecraft attitude dynamics is investigated in response to environmental disturbances including 1) lateral impulses, 2) gravity gradient, and 3) g-jitter forces. The purpose of this study is to investigate 1) how a rotating bubble of superfluid helium II reacts to the various environmental disturbances in conjunction with spacecraft attitude dynamics, 2) how amplitudes of slosh reaction forces and torques are induced and are activating on the Dewar coupled with attitude dynamics in response to impulse and environmental disturbances, and 3) how spacecraft translational displacement, velocity, and acceleration deviating from normal spacecraft operation are induced by the slosh dynamics driven by these disturbances. The numerical computation of slosh dynamics is based on a rotational frame, whereas the attitude dynamics is based on a nonrotational frame. The results show that major contributions to attitude 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 guidance and attitude control techniques.