Jōkyū War
The founder of the clan, Mōri Suemitsu, was the fourth son of Ōe no Hiromoto. He founded the clan when he took the name from his "shōen" named "Mōri" in Aikō District, Sagami Province. After the Jōkyū War, Suemitsu was appointed to the jitō office of a "shōen" in Aki Province. 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. The genealogy of the Mori clan is well verified because it matches up from several different sources such as the Mōri Family Tree (毛利系図), "Sonpi Bunmyaku" and Ōe Family Tree (大江氏系図).