Mōri Motonari (毛利 元就, April 16, 1497 – July 6, 1571) was a prominent daimyō (feudal lord) in the western Chūgoku region of Japan during the Sengoku period of the 16th century.

He was known as a great strategist who began as a small local warlord (jizamurai) of Aki Province and extended his clan's power to nearly all of the Chūgoku region through war, marriage, adoption and assassination.

Heavily outnumbered, the Mōri-led forces began to falter and fall back, rallying only when Motonari pleaded with them to stand their ground.

Motonari had thus already extended his influence north in the direction of the silver-rich Iwami Ginzan Silver Mine and south towards the Inland Sea.

The senior Mōri vassals met and decided to offer the leadership to Motonari and on August 10 he entered Yoshida-Kōriyama Castle as its new lord.

He paid a high price for the conquest, however, because Motonari's eldest daughter had been a political hostage of the Takahashi clan and was murdered by them in revenge.

[6] On September 25, 1533, Motonari was granted the imperial court rank of the Junior Fifth, Lower Grade in remembrance of his ancestor Ōe no Hiromoto's title.

In 1534, Motonari began consolidating the Mōri's holdings in Aki, gathering local allies, chief among these being the Shishido, Kumagai, and Amano.

[8] In August, Amago Haruhisa gathered a force of 30,000 and departed Izumo Province, moving into the vicinity of Motonari's Yoshida-Kōriyama Castle and establishing a headquarters nearby.

The Ōuchi relief army, consisting of 10,000 men led by Sue Takafusa,[8] finally departed Suō Province in November, pausing on Miyajima to offer prayers for victory at the Itskushima Shrine before landing in Aki and marching towards Yoshida-Kōriyama Castle.

In addition, Motonari took over the Kawachi Keigoshu (川内警固衆), a pirate organization owned by the Aki-Takeda clan, which would become a large part of the Mōri navy later.

In this battle they penetrated deep into the Amago clan territory but their supply line was broken and Kikkawa Okitsune (吉川興経) betrayed them.

In 1544 Motonari gave his third son, Tokujumaru (徳寿丸), for adoption to the Numata branch of the Kobayakawa clan (沼田小早川氏) who were famous for their naval forces.

After his defeat at the Siege of Toda Castle, Ōuchi Yoshitaka had grown tired of fighting battles and had retreated to work with literature and the arts.

In 1550 Motonari forced Motokane and many members of his household to commit suicide on the grounds of treasonous behavior, an act that secured the Mōri as Aki's most powerful family.

For his part, Sue made no major moves against Koriyama, and with the end of the year's campaigning season, Motonari was allowed some breathing space.

Harukata was by no means a poor fighter, and the danger of Motonari's retainers and allies deserting the Mōri led him to adopt a bold and unorthodox scheme.

Mōri's generals had suggested the occupation of Miyajima, which was strategically located just off the Aki coast in the Inland Sea, but Motonari had refused the idea on tactical grounds.

Naturally, such a tactic would require Sue's unwitting cooperation, and for inducement, Motonari immediately gave orders that Miyajima was to be occupied.

A fort, Miyao Castle, was thrown up quite near the Itsukushima shrine and Motonari proclaimed publicly his woe that it would not hold out long against an attack.

When the island had been secured (including the capture of Sakurao), Sue threw up a few fortifications on To-no-oka (Pagoda Hill) and sat down to plot strategy.

[12] As a diversion, Kobayakawa Takakage sailed straight past the Sue positions on To-no-oka while Motonari, Mōri Takamoto, and Kikkawa Motoharu landed just to the east and out of sight.

Takakage doubled back and landed at dawn, attacking the Sue forces practically in the shadow of Miyajima's great torii gate.

Supposedly, Motonari tricked Haruhisa into believing that Kunihisa and Era Fusahide (江良房栄) intended to take over the Amago clan.

The shōgun, Ashikaga Yoshiteru wished for peace between the Amago and Mōri clans, but Motonari ignored his plea and invaded Izumo Province in 1562.

Motonari's eldest son, Mōri Takamoto, while en route to attack the Amago clan in 1563, died of a sudden disease, though assassination by poison was suspected.

The battle of the Mōri clan with this larger allied force was part of Yamanaka Yukimori and Amago Katsuhisa's arrangement with Ōtomo.

[14] Shiji Hiroyoshi, Kuchiba Michiyoshi, Kumagai Nobunao, Fukubara Sadatoshi, Katsura Motozumi, Kodama Naritada, Kokushi Motosuke, Hiraga Hirosuke, and Ichikawa Tsuneyoshi assisted Mōri Motonari in his rule.

Surviving letters written by his grandson Mōri Terumoto describe Motonari as a strict and demanding man with a sharp eye.

Motonari often lives far beyond his means in popular culture, acting as the representative of his clan in affairs that take place far after his death (encountering Oda Nobunaga in the Mōri's later battles against him for just one instance).