Although Emperor Heizei tried to keep the ruling power after abdicating the throne to his brother, Emperor Saga did not welcome it, which led to a serious conflict between the two, and finally a military confrontation, in which Emperor Saga won (Kusuko Incident in 810).
平城は弟の嵯峨天皇に譲位した後も執政権を掌握し続けようとしたが、それを嫌った嵯峨との間に対立が深まり、最終的には軍事衝突により嵯峨側が勝利した（810年、薬子の変）。