Born the second son of Mōri Hiromoto, a minor local lord of Aki (Hiroshima).
He lost his mother young and his father at 9. A retainer seized his castle, and he lived so wretchedly that he was called "the beggar lordling", it is said. His father's concubine, Sugi no Ōkata, raised him with devotion.
At 20, in his first battle, he defeated the large army of Takeda Motoshige of Aki with few troops (Battle of Arita-Nakaide), sometimes called "the Okehazama of the west".
After his brother and nephew died in succession, he became head of the Mōri at 26. The house was then squeezed between two great powers, the Amago of Izumo and the Ōuchi of Suō.
The Amago besieged his home castle of Yoshida-Kōriyama with a huge army, but sheltering with the townspeople inside, he held out and drove them off with Ōuchi reinforcements.
By around this time he had his second son Motoharu adopted into the Kikkawa and his third son Takakage into the Kobayakawa, creating the "two rivers" system in which both houses supported the Mōri.
He lured the great army of Sue Harukata, who had overthrown his lord Ōuchi Yoshitaka, onto Itsukushima and routed it in a surprise attack on a stormy night, greatly expanding his power in the region.
In the year he destroyed the Ōuchi, he wrote a long letter to his three sons urging them to unite to protect the Mōri. The famous "three arrows" tale—one breaks, three together do not—is a later anecdote based on this letter.
His eldest son and heir Takamoto died suddenly, to Motonari's deep grief. His grandson Terumoto succeeded, with Motonari as guardian.
After a long struggle he took Gassan-Toda castle in Izumo and forced the Amago to surrender, becoming a great lord ruling nearly all of the Chūgoku region.
He died at Yoshida-Kōriyama castle at 74, a shrewd strategist who rose in one lifetime from minor local lord to master of the Chūgoku region.
Sue Harukata (Takafusa)Kikkawa MotoharuKobayakawa TakakageMōri TerumotoŌuchi YoshitakaAmago Tsunehisa
Amago TsunehisaHojo UjitsunaSaitō DōsanTaigen SessaiFrancis XavierŌuchi YoshitakaMatsunaga HisahideHōjō Ujiyasu
People of the Sengoku/Azuchi-Momoyama period ・ People by period
Based on facts found in textbooks and biographies. Uncertain points are marked as such.