The battle occured on October 21st 1600. So it only lasted 1 day.

sekigahara

matchlock guns

it was about generals fighting over a dead leader's power and rule.

Japanese General Ieysasu is victorious in the Battle of Sekigahara against the other regents of the son of late Japanese leader Oyotomi Hideyoshi. The victory took place on September 15, 1600 and solidifies his leadership over Japan. Ieysasu enlisted the help of Will Adams the English navigator to be his advisor. He also moved his capital from Kyoto to Edo, which became Tokyo.