Conflict with Ishida Mitsunari According to popular theory, after the death of Toyotomi Hideyoshi in 1598, the government of Japan was shaken by an incident, where seven military generals —
Fukushima Masanori, Katō Kiyomasa,
Ikeda Terumasa,
Hosokawa Tadaoki,
Asano Yoshinaga,
Katō Yoshiaki, and
Kuroda Nagamasa—conspired to kill Ishida Mitsunari. Supposedly the group was disstatisfied with Mitsunari, as he wrote bad assessments and underreported the achievements of those generals during the Imjin war against Korea and the Chinese empire. When the conspirators found out that Mitsunari was not in his mansion, they searched the mansions of various feudal lords in Osaka Castle, and Kato's army also approached the Satake residence. Mitsunari and his party escaped and barricaded themselves at
Fushimi Castle. The next day, the seven generals surrounded Fushimi Castle with their soldiers as they knew Mitsunari was hiding there.
Tokugawa Ieyasu, who was in charge of political affairs in Fushimi Castle tried to arbitrate the situation. The seven generals requested Ieyasu to hand over Mitsunari, which was refused. Ieyasu then negotiated the promise to let Mitsunari retire and to review the assessment of the Battle of Ulsan Castle, which had been the major source of this incident, and had his second son,
Yūki Hideyasu, escort Mitsunari to Sawayama Castle. However, historian Watanabe Daimon stated that, from the primary and secondary sources about the incident, that it was more of legal conflict between those generals and Mitsunari, rather than a conspiracy to murder him. The role of Ieyasu was not to protect him from any physical harm, but to mediate the complaints of the seven generals. Nevertheless, historians viewed this incident not just as simply personal problems between the seven generals and Mitsunari, but rather as an extension of the political rivalries between the Tokugawa faction and the anti-Tokugawa faction led by Mitsunari. After the incident, military figures on bad terms with Mitsunari would support Ieyasu during the
Sekigahara campaign between the Eastern Army led by Tokugawa Ieyasu and the Western Army led by Ishida Mitsunari. According to Muramatsu Shunkichi, writer of
The Surprising Passions and Desires of the Heroes and Heroines of Japanese History, the reason for Mitsunari failure in his war against Ieyasu was his unpopularity among the major political figures of that time. After the incident, Kiyomasa joined forces with
Tokugawa Ieyasu and during the Sekigahara campaign (August–October 1600) fought Ishida's allies on
Kyushu, taking a number of castles. He was preparing to invade the
Shimazu domain when the campaign ended and Ieyasu ordered him to stand down. For his service, Katō was awarded the other half of
Higo, bringing his income to nearly 500,000 koku. ==Death==