He was defeated by Hōjō Tokiyori in 1247 and committed suicide (seppuku) at Minamoto no Yoritomo's shrine (hokkedō) along with his Miura clan allies.

[4] According to the Sonpi Bunmyaku (尊卑分脈) from the late 14th century:[5] During the Kamakura shogunate the Mōri were a gokenin family due to the fame of their ancestor Ōe no Hiromoto.

Mōri Suemitsu, the fourth son of Ōe no Hiromoto inherited Mōri-shōen from his father and that is why he began to use the name.

The second battle took place in 1579 with the Oda sending eight Atakebune (heavily armoured ships with iron-clad plating) warships to finally destroy the Mōri naval threat.

After a struggle between Toyotomi Hideyoshi, who led his army as a general of Oda Nobunaga, the two sides made peace and Mōri remained as a daimyō who kept six provinces in Chūgoku.