The Iriki-In clan's capture of Iwaya Castle in a single night raid consolidated Shimazu Takahisa's authority during a period of internal clan rivalry in Satsuma Province.
Key Facts
- Date of battle
- 9 October 1539
- Castle contested
- Iwaya Castle (also known as Momotsugi Castle)
- Castle granted to Iriki-In
- 1536, by the Shimazu clan
- Method of capture
- Single night raid by Iriki-In forces
- Province
- Satsuma Province
Location
Cause → Event → Consequence
Shimazu Sanehisa, a branch member of the Shimazu clan, rebelled against Shimazu Katsuhisa in 1526 and seized control of Satsuma Province, causing a split in clan loyalty. Although Iwaya Castle had been granted to the Iriki-In clan by the Shimazu in 1536, Sanehisa's forces continued to occupy it, prompting Iriki-In Shigetomo to act in support of Katsuhisa's successor, Shimazu Takahisa.
On 9 October 1539, Iriki-In Shigetomo led an Iriki-In army loyal to Shimazu Takahisa in a surprise night raid on Iwaya Castle. The assault was swift and decisive, allowing Shigetomo to seize the castle in a single operation from the rival forces loyal to Shimazu Sanehisa.
Shigetomo successfully secured Iwaya Castle, asserting possession based on the prior grant of 1536. His bold action earned him considerable praise and respect from Shimazu Takahisa, reinforcing the Iriki-In clan's standing as loyal allies and strengthening the main Shimazu line's effort to reassert control over Satsuma Province.
Belligerents & Mobilization Analysis
Side A
1 belligerent
Iriki-In Shigetomo.
Side B
1 belligerent
Shimazu Sanehisa.