The Kantō-Kyōroku Conflict occurred from Kyōroku 2 to 4 (1529 to 1531). This was comprised of internal conflicts in the family of the Koga kubō and the Yamanouchi-Uesugi family of the deputy shōgun of the Kantō which broke-out and ended at approximately the same times. The two events are surmised to have been interrelated but authenticated accounts of these conflicts are scarce so the details are uncertain.
During the Muromachi and Sengoku periods, numerous military families (including the shōgun family of the bakufu) were beset by succession conflicts as well as power struggles between the lineal branch and illegitimate branches of the families. From the outbreak of the Kyōtoku War in 1454, the family of the Koga kubō and the Yamanouchi-Uesugi family of the deputy shōgun of the Kantō, as the most influential military families in the Kantō, were no exceptions to the discord. In the family of the Koga kubō, Ashikaga Masauji (the second Koga kubō) came into conflict with his eldest son, Ashikaga Takamoto (the third Koga kubō) over succession. At the same time, in the family of the deputy shōgun of the Kantō, Uesugi Akizane (aligned with Masauji) and Uesugi Norifusa (aligned with Takamoto) also came into conflict over succession which then enveloped many other military families, escalating into a large-scale struggle known as the Eishō Conflict that ran from 1506 to 1518.
Meanwhile, the succession from Takamoto to Ashikaga Haruuji (the fourth Koga kubō) reignited internal conflicts although not on the same scale as the Eishō Conflict.
Family of the Koga kubō
On 12/27 of Kyōroku 1 (1528), Ashikaga Haruuj, the lineal heir to the family of the Koga kubō, attended his coming-of-age ceremony.
In 1529, Satomi Yoshitoyo of Awa Province proposed Ashikaga Haruuji as the head of the Ashikaga family of the Koga kubō. This suggested a conflict between Ashikaga Takamoto and Haruuji.
On 5/31 of Kyōroku 2 to 4, Haruuji attacked Takamoto’s base at Koga Castle.
On 6/1 of Kyōroku 4 (1531), based on a letter from Ashikaga Masauji to Ashikaga Takayori, Ashikaga Haruuji investigated whether to return from Shimotsuke-Utsunomiya Castle to Koga Castle. This suggested that the conflict was close to ending and that Utsunomiya Okitsuna and Haga Jirō were on the side of Haruuji, Masauji was on the side of Haruuji, and Ashikaga Motoyori and Narita Chikayasu of Oshi Castle in Musashi Province were on the side of Masauji.
On 6/6 of Kyōroku 4 (1531), Haruuji, in his role as the Koga kubō, instructed Tashiro 三輝斎 (from the hōkōshū, or military organ under the direct control of the shōgun) to provide medical treatment to Ashikaga Masauji. This indicated that, as of this time, Haruuji had secured his position as the Koga kubō.
On 6/9 of Kyōroku 4 (1531), Takamoto informed Koyama Koshirō of his retirement and requested his continued service to the Koga kubō. This indicated an end to the conflict.
Yamanouchi-Uesugi family – deputy shōgun of the Kantō
On 1/24 of Kyōroku 2 (1529), Shiroi-Nagao Kagenobu, a retainer of the Yamanouchi-Uesugi family, was murdered by Nagao Hachirō, highlighting conflict within the Yamanouchi-Uesugi family.
On 8/14 of Kyōroku 2 (1529), Uesugi Norihiro (the head of the Yamanouchi-Uesugi) commenced a campaign to subdue the Annaka clan at Annaka Castle in the Usui District of Kōzuke Province. Uesugi Tomooki from the Ōgigayatsu-Uesugi who was allied with the Annaka attempted to restrain Norihiro but was ignored.
On 9/22 of Kyōroku 2 (1529), the Nishi and Obata clans backed Uesugi Norimasa and launched a rebellion against Uesugi Norihiro. Norihiro had the Nagano clan accompany him and withdrew from Annaka Castle to Hodota. Tensions between the Nagano and Annaka clans existed in the background of Norihiro’s subjugation of the Annaka clan.
In the fifth month of Kyōroku 3 (1530), Saemon-no-jō issued a ban against the Jinsō Temple in the Tago District of Kōzuke Province, indicating battles within the territory of the Yamanouchi-Uesugi clan.
On 5/21 of Kyōroku 3 (1530), Uesugi Norihiro, upon the urging of Takada Noriyori, issued a written commendation to a retainer named Moriyama Yogorō for his military contributions. This indicates that Noriyori was aligned with Norihiro and there was a battle in the environs of Takada Castle in the Kanra District of Kōzuke Province.
On 10/25 of Kyōroku 3 (1530), Uesugi Norihiro granted the territory of Yōdo Shinsaburō in Akahama in the Obusuma District of Musashi Province to a servant named Santome Heiroku, indicating that the Yōdo clan was in conflict with Norihiro.
On 9/3 of Kyōroku 4 (1531), Uesugi Norimasa succeeded to the role of the deputy shōgun of the Kantō and Norihiro withdrew to Miyahara in Kazusa Province, adopting the name of Harunao. Thus, Norimasa prevailed and the conflict came to an end.
In the family of the Koga kubō, Ashikaga Haruuji secured his position as the fourth head of the family while Takamoto retired. In the family of the Yamanouchi-Uesugi, Uesugi Norimasa inherited the headship of the clan while Norihiro lost and retired to Miyahara in Kazusa Province.
The Ōgigayatsu-Uesugi clan were also affected by the conflict. At the end of 1528, their conflict with the Gohōjō clan had escalated, but they could not turn for support to the Yamanouchi-Uesugi clan and Koga kubō so Uesugi Tomooki entered into an alliance with Takeda Nobutora of Kai Province.
Compared to the Eishō Conflict, there is a weaker connection in these conflicts between the internal discord in the family of the Koga kubō and in the Yamanouchi-Uesugi family and other military families were not drawn into the disputes as in the Eishō Conflict. Power struggles within each of the territories featured prominently and, in the Kyōroku period, the family of the Koga kubō and the Yamanouchi-Uesugi family were each establishing themselves as regional powers.