Prior to his death, Hideyoshi tried to entrust political
affairs of the representative system to the leading daimyos etc.
He worried about whether or how he should protect, young Hideyori and make him a ruler to prevent the possible emergence of Ieyasu, who would become the leader. A result of the representative system.
Hideyoshi had taken the wrong action towards his retainer in the Hidetsugu incident, the Position of Bunroku, the Position of Keichou. Therefore, inside the Toyotomi Administration was a whirling tornado of dissatisfaction. It was subvisive to say that government did not have a strong foundation, that it was not a monolith.
The military superintendent officer and the prefect of the Bnchi-group were opposed by the general of the Budan-group over strategy, In addition, the fight over idea success and the assessment of the battle for Ulsan castle was a serious problem.
The dispute between the Bunchi-group and the Budan-group did not often surface during the rein of Hideyoshi. When Hideyoshi died, the dispute of the Bunchi-group and the Budan-group became violent and the hatred for Mitsunari Ishida, who was the head of the Bunchi-group reached a climax.
Toshiie Maeda was in an arbitrate position during the fights of the Bunchi-group and the Budann-group. However, Toshiie died, in 1599 and Mitsunari Ishida was attacked by
the Seven commanders of the Budan-group.
The seven commanders who gathered in a mansion of Kiyomasa Kato tried to catch Mitsunari, who escaped to the Fushimi Castle. However, Ieyasu Tokugawa, who had taken control of Fusihmi Castle, protected Mitunari from Kato’s armies.
Ieyasu made a promise to the Seven commanders, that forced Mitsunari to resign from his Bugyo post and made him stay in Sawayama Castle. Furthermore, Ieyasu proposed reexamination of the battle of the Korean Ulsan castle. Ieyasu took control of the situation and let Mitsunari go to Sawayama Castle.
In the autumn of the same year, An assassination of Ieyasu plotted by the Gotairo Toshinaga Maeda and others came to light (known as the Kaga rebellion theory)
Ieyasu issued a fiat to the daimyos to conquer the Kaga area Toshinaga decided to send his birth mother to Ieyasu as a hostage, therein Toshinaga maintained his innocence. And he kept the situation under control.
For punishment, Gobugyo Nagamasa Asano was ordered to be placed under house arrest in Musashi, and the Gotairo Toshinaga was taken in by the Ieyasu group. The Gotairo and the Gobugyo’s post as adviser to Hideyori, according to the will of Hideyosi, was annulled.
Ieyasu managed the marriages between daimyo (the daughter who got engaged became an adopted daughter of Ieyasu), Ieyasu borrowed the name of Hideyori and performed adding to daimyos. Ieyasu steadily extended his power.
And Ieyasu called upon his strong generals of the Budan-group that ran about the battlefield and helped to control the entire country with Hideyoshi.Furthermore, Ieyasu approached Kitano, who was well loved by strong generals, and Ieyasu succeeded in adding combat veterans to his command.
Moreover, many daimyos read the current of the times. They believed that Ieyasu would rule Japan., so they joined Ieyasu.