Key Facts
- Attacker force size
- 30,000 men (Amago)
- Defender force size
- 8,000 men (Mōri)
- Siege duration
- ~4 months (Oct 1540 – Feb 1541)
- Period
- Sengoku period
Strategic Narrative Overview
The Amago force vastly outnumbered the 8,000 defenders holding Yoshida-Kōriyama Castle. Mōri Motonari organised the defence and held out through the autumn and into winter. The siege dragged on for approximately four months without the attackers breaking through the castle's defences. The prolonged standoff gave time for outside intervention to alter the strategic balance.
01 / The Origins
During Japan's Sengoku period, regional warlords competed for territorial dominance in western Honshū. Amago Haruhisa sought to expand his clan's influence westward into Aki Province. Yoshida-Kōriyama Castle, the stronghold of Mōri Motonari, represented a key obstacle to Amago ambitions. In October 1540, Haruhisa mobilised a force of 30,000 men to besiege the castle and dislodge Mōri from his power base.
03 / The Outcome
The Ōuchi clan, rivals of the Amago and allied with Mōri, dispatched a relief army under commander Sue Harukata. Faced with this approaching force, Amago Haruhisa was compelled to abandon the siege in February 1541 and withdraw. The failed siege preserved Mōri Motonari's domain and demonstrated the limits of Amago power in western Japan.
Belligerents & Mobilization Analysis
Side A
1 belligerent
Amago Haruhisa.
Side B
2 belligerents
Mōri Motonari, Sue Harukata.
Kinetic Engagement Axis
Scroll horizontally to view full axis. Events plotted relatively.