Siege of Kuwabara
1542 CE.
Shown on the map at 36.026°, 138.140°.
The siege of Kuwabara took place the day after the siege of Uehara; Takeda Shingen continued to gain power in Shinano Province by seizing Kuwabara castle from Suwa Yorishige. Suwa was escorted back to the provincial capital of Kōfu under "the pretext of safe conduct, but he was then forced to commit suicide."
Text from the Wikipedia article Siege of Kuwabara, licensed CC BY-SA 4.0.