The Siege of Fushimi Castle occurred from 7/18 to 8/1 of Keichō 5 (1600) as a preliminary clash to the main Battle of Sekigahara between the Eastern and Western armies.

Prelude

After the death of Toyotomi Hideyoshi, Tokugawa Ieyasu (one of the Council of Five Elders) decided to launch the Conquest of Aizu to subdue Uesugi Kagekatsu in Mutsu Province for rebelling against the Toyotomi administration.  On 6/18 of Keichō 5 (1600), he departed Fushimi Castle to march east toward Aizu.

Meanwhile, on 7/17, three magistrates in Ōsaka Castle (Maeda Gen’i, Mashita Nagamori, Natsuka Masaie) expelled from the western citadel of the castle those individuals whom Ieyasu had assigned to serve in his absence and issued a written censure of Ieyasu with thirteen conditions.  Prior to this event, on 7/15, Fushimi Castle where retainers of Ieyasu such as Torii Mototada were located was locked down, and the Western Army opposed to Ieyasu prepared to attack.

The garrison of 1,800 soldiers defending the castle were joined by 500 troops coming from the western citadel of Ōsaka Castle, reaching a total force of 2,300.

Course of events

From 7/19, the battle began in earnest.  Initially, some of those in the castle charged out to engage the attacking forces, burning down the residence of Maeda Gen’i and Natsuka Masaie, but, thereafter, the attacking forces rained arquebus fire on the castle day and night.  On 7/22, forces led by Ukita Hideie joined to increase the pressure on the defenders.  The attackers constructed Mount Tsuki for the placement of cannons and filled-in the moat, but the fortified castle did not easily fall.  Nevertheless, the isolated castle finally fell around noon on 8/1.  Torii Mototada was killed by Suzuki Shigetomo (the commander of the infantry forces) while a total of 800 soldiers including Naitō Ienaga, Matsudaira Ietada, Hayashi Chikuan, and Udono Ujitsugu perished.

Local residents observed the clashes at Fushimi Castle from nearby Mount Ogurisu.

Aftermath

This conflict occurred for a period of over ten days prior to the main Battle of Sekigahara on 9/15 of Keichō 5 (1600).  There is a theory that this was a cause of significant delay in the subsequent build-up of the Western Army in the direction of Mino and Ise provinces.

There is a theory that, Shimazu Yoshihiro and Kobayakawa Hideaki initially sought to ally with the Eastern Army so expressed a desire to enter the castle on behalf of the defenders, but were refused so inevitably joined the Western Army to attack the castle.

Each of the foregoing theories is based on secondary materials written in the Edo period and therefore cannot be authenticated as historical facts.

After the battle, the armor owned by Torii Mototada was transferred to Suzuki Shigetomo but Shigetomo proposed returning it to Mototada’s son, Tadamasa.  Tadamasa was greatly appreciative but returned the armor to Shigetomo.  In 2004, the armor was gifted by the Suzuki family to a museum in the main citadel of Ōsaka Castle.  The helmet was reconditioned at the end of the Edo period.