During the Battle of Dan-no-ura, the divine sword sunk in the sea along with Nii no Ama when he committed suicide by drowning while holding Emperor Antoku and wearing the sword on his side.
皇居の神剣（天叢雲剣の形代）は、源平の壇ノ浦の戦いにおいて、二位の尼が安徳天皇を抱き腰に神器の剣を差して入水したため一緒に水没した。