Siege of Ōtsu Castle
Year: 9/7 to 9/15 of Keichō 5 (1600)
Location: Ōtsu Castle in the Shiga District of Ōmi Province
Outcome: After switching allegiance to the Eastern Army, Kyōgoku Takatsugu holed-up in Ōtsu Castle during a siege led by Suetsugu Motoyasu of the Western Army. After approximately one week, he vacated the castle after mediation and was later awarded a fief by Tokugawa Ieyasu for indirectly contributing to victory by the Eastern Army at the Battle of Sekigahara (by having drawn 15,000 forces from the Western Army to the siege). The capture of Ōtsu Castle became meaningless following the loss by the Western Army that same day at the Battle of Sekigahara.
The Siege of Ōtsu Castle occurred from 9/7 to 9/15 of Keichō 5 (1600) at Ōtsu Castle in the Shiga District of Ōmi Province. This conflict was a prelude to the Battle of Sekigahara that occurred on 9/15 of Keichō 5 (1600).
After the demise of Toyotomi Hideyoshi on 8/18 of Keichō 3 (1598), the confrontation between Tokugawa Ieyasu and Ishida Mitsunari became apparent on the occasion of the Conquest of Aizu. Mitsunari took advantage of Ieyasu’s absence during this time to summon assorted daimyō including Ōtani Yoshitsugu and Mōri Terumoto and launch a rebellion. While Ieyasu was away from the Kinai area, Mitsunari toppled Fushimi Castle and then aimed to pacify the Hokuriku Region as well as Ise Province.
Ōtani Yoshitsugu of Tsuruga in Echizen Province was given responsibility for pacification of the Hokuriku Region. Kyōgoku Takatsugu, the lord of Ōtsu Castle in Ōmi Province, served as a member of this army. However, while Yoshitsugu was in the process of changing the direction of his advance from the Hokuriku to Mino Province, Takatsugu suddenly betrayed Yoshitsugu in favor of the Eastern Army, holed-up in Ōtsu Castle with a garrison of 3,000 men, and prepared for defensive operations. Before Tokugawa Ieyasu deployed on his expedition to eliminate the Uesugi, he held discussions with Takatsugu at Ōtsu Castle and obtained his support. There is a theory that while Takatsugu was originally a member of the Eastern Army, he appeared receptive to the Western Army, but Mitsunari and other commanders were not aware of this fact. In a letter dated 9/12 of 1600 from Mitsunari to Mashita Nagamori, Mitsunari regreted overlooking the connection between the role of Kyōgoku Takamoto (Takatsugu’s younger brother) as a commander in the Eastern Army and the possibility that Takatsugu was also aligned with the Eastern Army.
In any event, Ōtsu Castle was located on the southwest shore of Lake Biwa and served as a base for marine transport. Below the castle the Tōkai, Nakasen, and western Ōmi roads came together, making this a strategic location for the Western Army that connected Kyōto and the vicinity as well as for their advance to Echizen, Mino, and Ise. While Takatsugu and his forces were in the castle, a messenger arrived from Ōsaka Castle. The messenger was sent to protect Hatsu (known as Jōkō-in – the formal wife of Takatsugu) and Tatsu (known as Matsu-no-maru-dono – the younger sister of Takutsugu) who were in the castle with Takatsugu. This owed to their familial ties to Yodo-dono – a consort of Toyotomi Hideyoshi.
On 9/7 of 1600, the Western Army commanded by Suetsugu Motoyasu and comprised of 15,000 forces with several daimyō from Kyūshū including Tachibana Muneshige, Kobayakawa Hidekane, and Tsukushi HIrokado, began to lay siege to Ōtsu Castle. Attacks against the castle, however, did not proceed well. This included when Akao Izu-no-kami and Yamada Ōi led 500 soldiers out of the castle to attack. After growing weary of the prospects for an assault, on 9/13, the besieging forces fired cannons at the castle. The shells stuck the main citadel, triggering chaos among the defenders. Takatsugu also engaged in the defensive, while Tachibana Kichiemon of the Western Army commanded a vanguard unit in an effort to breach the castle walls.
Led by Takatsugu, on 9/15, the Kyōgoku forces surrendered and vacated the castle after mediation by a priest named Mokujiki Ōgo. Ultimately, Ōtsu Castle did not fall as a result of military force, but through the persuasion of a messenger sent from Ōsaka Castle. Takatsugu’s life was spared, after which he went to Mount Kōya and entered the priesthood.
The siege of Ōtsu Castle resulted in a victory for the Western Army, but the castle was vacated on the same day as the decisive Battle of Sekigahara. This meant that the 15,000 soldiers participating in this siege were absent from the other battle against the Eastern Army. Owing to the defeat of the Western Army at the Battle of Sekigahara, the capture of Ōtsu Castle lost its meaning by the end of that same day.
After Tachibana Muneshige took control of Ōtsu Castle, he led his forces to Kusatsu in the Kurita District of Ōmi. After learning of the defeat of the Western Army, he was compelled to retreat with his forces to Ōsaka Castle and, in the aftermath, was removed from his position.
In the Battle of Sekigahara, Kyōroku Takamoto (Takatsugu’s younger brother), made contributions as a commander in the Eastern Army. After Takatsugu had moved to Mount Kōya in the aftermath of his surrender at Ōtsu Castle, Tokugawa Ieyasu dispatched Takamoto to Mount Kōya and offered Takatsugu a pardon along with the status of a daimyō, governance of Wakasa Province and a fief of 85,000 koku. In the following year, his fief was increased by 7,100 koku in the Takashima District of Ōmi, amounting to total holdings of 92,100 koku. Ieyasu is believed to have awarded Takatsugu for drawing Muneshige and others to Ōtsu Castle and not directing them to Sekigahara.