In terms of what it depicts, could it be this? The Battle of Dan-no-ura? April 25th, 1185
https://en.wikipedia.org/wiki/Battle_of_Dan-no-ura
To this day, the Heike Crabs found in the Straits of Shimonoseki are considered by theJapanese to hold the spirits of the Taira warriors. The Taira attempted to toss the imperial regalia off the ship but only managed to get the sword and jewel into the water before the ship holding the regalia was captured. [5]
The jewel was recovered by divers; many presume the sword to have been lost at this time, though it is officially said to have been recovered and enshrined at Atsuta Shrine.
This decisive defeat of the Taira forces led to the end of the Taira bid for control of Japan. Minamoto Yoritomo, the elder half-brother of Minamoto Yoshitsune, became the first Shogun, establishing his military government ('bakufu') in Kamakura. In this battle the Taira lost Taira Tomomori, Taira Noritsune, Taira Norimori, Taira Tsunemori, Taira Sukemori, Taira Arimori and Taira Yukimori, who were killed.