The Battle of Tanabe-jo Castle (田辺城の戦い)
After the death of Hideyoshi TOYOTOMI, Ieyasu TOKUGAWA, who was seeking the post of tenkabito (the ruler of the kingdom), began invading the Aizu Domain to attack Kagekatsu UESUGI's army in 1600, claiming that UESUGI was a treacherous retainer who rebelled against the administrative authority because he had often ignored the order to go to the capital. After Ieyasu's army proceeded to the east, the territories in the vicinity of the capital became an area with no military presence. Seeing this situation, Mitsunari ISHIDA, who had been taking sides against Ieyasu, raised an army in advocacy of the Toyotomi clan. This marked the beginning of the battle between the eastern army lead by Ieyasu TOKUGAWA and the western army lead by Mitsunari ISHIDA.
The western army lead by Mitsunari ISHIDA first tried to gain ascendancy over various Daimyo who were on Ieyasu's side, in the territories in the vicinity of the capital to conquer their territories. One of the territories was Tanabe-jo Castle in Tango, the lord of which was Tadaoki HOSOKAWA. Tadaoki HOSOKAWA was one of the Budanha (Budan factions) of the Toyotomi clan and had been taking sides against Mitsunari ISHIDA. Therefore, while Tadaoki HOSOKAWA was joining the army to attack the Aizu Domain as a member of the eastern army, Mitsunari ISHIDA raised an army of 15,000 soldiers mainly consisting of various Daimyo of Tanba Province and Tajima Province, such as Shigetsugu ONOGI (Kimisato ONOGI), Shigekatsu MAEDA, Nobukane ODA, Yoshimasa KOIDE, Nagafusa SUGIHARA, Moritomo TANI, Nagakatsu FUJIKAKE and Nagamasa HAYAKAWA, all of whom were members of the western army, to attack and capture Tanabe-jo Castle.
At this time, Tanabe-jo Castle was protected by the remaining 500 soldiers lead by Yusai HOSOKAWA, the father of Tadaoki. Despite the intense resistance of Yusai, it was unlikely that Yusai and his soldiers would have been able to fight equally against ISHIDA's army due to the lack of hope of support and the visible difference in force size, and accordingly, the battle to capture the castle started on July 19, and the castle was nearly captured by the end of July. However, there were quite a few soldiers including Onogi, who looked up to Yusai as their mentor of tanka poetry, in the western army. Therefore, they were hesitant to capture Tanabe-jo Castle.
At the same time, Emperor Goyozei of the Court was afraid that Yusai would die in battle. Yusai was a successor of tanka poetry, who relayed the arcana, from ancient to modern, by Kineda SANJONISHI. Therefore, the Emperor sent a vassal to tell Yusai to surrender the castle, but Yusai refused because of his own personal honor as a samurai and gave the anthology of waka poems from ancient to modern times with the certificate to the Emperor and Imperial Prince Hachijonomiya Toshihito (younger brother of Emperor Goyozei).
The Emperor, however, was seriously concerned for Yusai's life. It was because Yusai had been not only a master of tanka poetry but also a familiar person among the court nobles since the period of Yoshiaki ASHIKAGA. For this reason, the Emperor sent Saneyo SANJONISHI (Chief Councillor of State), Michikatsu NAKANOIN (Vice-councillor of State) and Mitsuhiro KARASUMARU (Konoefu naibukanshoku (a post guarding inside the palace and imperial families)) as Imperial messengers to both the eastern army and western army at Tanabe-jo Castle in order to propose a royal peace command. The western army with Onogi, which was becoming dominant, was not able to refuse the royal command because it was a command from the Emperor, and Yusai surrendered Tanabe-jo Castle to the western army and entered Kameyama-jo Castle, the lord of which was Shigekatsu MAEDA, the enemy general, in Tanba on September 6.
The western army won the Battle of Tanabe-jo Castle in terms of results but lost in strategic terms. This is because the western army with Onogi, consisting of various Daimyo of Tanba and Tajima, did not make it to the Battle of Sekigahara, which started 9 days after the western army captured the castle from Yusai on September 6. It was significant that 15,000 soldiers were unable to make it to the main part of the Battle of Sekigahara. It can be said that this was a strategic setback for the western army.