The Enshū Discord, or Enshū sōgeki, occurred from Eiroku 5 (1562) to Eiroku 9 (1566) primarily in the Tenryū River Basin of Tōtōmi Province.  This was a large-scale rebellion by kunishū, or provincial landowners, against the Suruga-Imagawa clan.

Political situation

In the early Sengoku period, the Suruga-Imagawa invaded Tōtōmi Province.  In 1517, Imagawa Ujichika achieved a major victory, defeating the Shiba clan (who were serving as the military governors of Tōtōmi), killing Ōkōchi Sadatsuna (the local governor of the Hamamatsu manor), and capturing alive Shiba Yoshitatsu, a sengoku daimyō and the thirteenth head of the Shiba clan.  Thereafter, Tōtōmi was folded into the territory of the Imagawa clan while the Iinoo, the Amano, the Ii, and other kunishū fell under the command of the Imagawa.

Following the death of Ujichika, Tōtōmi and neighboring Mikawa Province were under the control of Imagawa Ujiteru and then his younger brother, Imagawa Yoshimoto, as territory of the Imagawa.  In 1560, Yoshimoto was killed by the Oda army at the Battle of Okehazama.  This marked a turning point.  In the wake of this event, Imagawa Ujizane inherited the Imagawa clan.  In the third month of 1561, the Gohōjō clan (allies of the Imagawa) incurred an invasion of the Kantō by Uesugi Kenshin.  The dispatch of Imagawa troops as reinforcements to the Gohōjō in addition to an assault on Ushikubo Castle in Mikawa by Matsudaira Motoyasu (later known as Tokugawa Ieyasu) in the fourth month triggered defections from the Imagawa, leading to an unstable situation.  Mikawa was divided between kunishū who supported the Imagawa and those supporting the Matsudaira, resulting in conflict that split the province.  Ashikaga Yoshiteru and Hōjō Ujiyasu made efforts to facilitate a settlement between the Imagawa and Matsudaira, but these efforts failed while the conflict persisted owing to the actions of both parties.

Instability in Mikawa Province eventually spread to neighboring Tōtōmi.  From around 1565, kunishū began to rebel against the Imagawa clan in large numbers across Tōtōmi.

Course of the rebellion

Rebellion by the Ii clan

In either the third or twelfth month of 1562, Ii Naochika, the head of the Ii clan, a member of the kunishū based in Iinoya, colluded with the Matsudaira clan whereupon Imagawa Ujizane had him executed at Kakegawa Castle.  This is deemed to have triggered the Enshū Discord, but the rebellion by the Ii clan is noted only in genealogical records of the Ii clan drafted in later eras which do not constitute a primary source.  Therefore, the fact of the rebellion cannot be definitively confirmed.

Rebellion by the Iinoo clan

The Iinoo clan originally served as local governors of the Hamamatsu manor of the Mikawa-Kira clan.  Following the invasion of Tōtōmi by Imagawa Ujichika, the Iinoo affiliated with the Imagawa, becoming kunishū with landholdings in the environs of Hikuma Castle.  Inoo Tsuratatsu, the head of the Iinoo, colluded with the Matsudaira clan and, in the twelfth month of 1563, defected from the Imagawa.  Iinoo Tosa and Ema Yashichi, retainers of the Iinoo clan, holed-up in Zudaji Castle.  At the Battle of Iidaguchi, the Imagawa defeated the Iinoo.  Afterwards, Ujizane provided letters of commendation to Fuji Matahachirō, Ogasawara Kiyoari, and Asahina Nobuoki.  In the second month of 1564, a battle occurred at the gateway to Hikuma.  It appears that the Imagawa struggled in their efforts to suppress the rebellion by the Iinoo clan.  In the fourth month, Tsuratatsu met with Matsudaira Ieyasu, the Matsudaira army stormed the Washizu-Honkō Temple and attacked Imagawa forces across the province.

In the tenth month, Ujizane pardoned Tsuratatsu and ordered the destruction of Zudaji Castle where Tsuratatsu had holed-up.  In the twelfth month, it was discovered that Tsuratatsu was colluding with the Matsudaira so, on 12/20, Tsuratatsu was executed by Ujizane.  Thereafter, the band of retainers of the Ino-o clan continued to collude with the Matsudaira and resist the Imagawa.  Chief retainers of the Inoo, Ema Tokinari and Ema Yasuaki received written oaths from retainers of the Matsudaira, Ishikawa Kaumasa and Sakai Tadatsugu, promising additional forces.

The rebellion by the Ema clan appears to have ended as of 4/21 of Eiroku 9 (1566) after Ujizane provided official recognition of their rights to their landholdings.

Rebellion by the Amano clan

The Amano clan were one of the kunishū competing for influence in the Sankō manor.  The Amano collaborated with the Imagawa during the invasion of Tōtōmi and were subordinate to the Imagawa.  While there were many branches of the Amano clan, those wielding the most power included this main branch in addition to the lineages under the name of Shichirō (Aki-no-kami) and Kūnaiemon-no-jō which gained prominence for contributing to the invasion of Tōtōmi by the Imagawa.  At this time, Amano Kageyasu was the heir of the Aki-no-kami branch.  He vied with Amano Fujihide of the Kūnaiemon-no-jō branch in regard to governance of the territory and inheritance rights.  In the second month of 1562, claims arose the involved the Imagawa clan.  On this occasion, the Imagawa issued a verdict favorable to Fujihide which, in turn, invited the scorn of Kageyasu.  In the twelfth month of 1563, he then launched a rebellion against the Imagawa clan.

The rebellion was not supported by servants who were discontent with the military service requirements of Kageyasu.  Moreover, Amano Fujihide from the same family remained on the side of the Imagawa and joined the army to suppress the rebellion.  By joining forces with Onoe Masayoshi, he was able to suppress the rebellion that same month.  Thereafter, Fujihide became the heir of the Amano clan and continued to exist as a kunishū subordinate to the Imagawa.

Rebellion by the Okuyama clan

The Okuyama clan were kunishū with landholdings in the Okuyama township of the Sankō manor.  The Okuyama shared the same sentiments as the Amano clan.  Okuyama Yoshikane, the heir of the clan at the time, sympathized with his guardian parent, Amano Kageyasu, and rebelled, but Okuyama Sadatomo and Okuyama Tomohisa (siblings from an illegitimate branch of the family) remained on the side of the Imagawa so the Imagawa recognized their positions in the manor.  The rebellion by Yoshikane was soon quelled so, unlike the Amano clan, he was able to continue governing the Okuyama township.  As a result, the Imagawa granted Sadatomo and Tomohisa the Upper Nagao township as substitute landholdings.  Together with Amano Fujihide and Amagata Mikawa-no-kami, they constructed Nakabiu Castle to prepare defenses against the rebel army.  It appears that the rebels including Yoshikane continued to govern the Okuyama township until the decimation of the Imagawa clan in 1569.

Other

In addition to the above, Matsui Munetsune of Futamata Castle and Horigoshi Ujinobu of Mitsukeha Castle are deemed to have defected to the Imagawa but the details cannot be confirmed from authenticated records.  There is a document dated 10/21 of Eiroku 6 (1563) in regard to the Matsui clan in which, owing to the rebellion by Munetsune, the Horigoshi township in Tōtōmi conveyed to his grandfather, Matsui Sadamune, who remained on the side of the Imagawa.  It is not established, however, that there is a direct connection to the series of rebellions.  There is also a prohibition dated 2/25 of Eiroku 7 (1564) issued by Imagawa Ujizane to the head of the Hachiman Shrine in the territory of Futamata suggesting that at this time the Imagawa army was attacking in the direction of Futamata Castle.  In the course of the Enshō Discord, Saigō Nobufusa and Saigō Iyo-no-kami from the same Tōtōmi-Saigō clan who were landowners in the Saigō manor in the Sano District quarreled among themselves, after which Nobufusa (a supporter of the Imagawa) ultimately prevailed and acquired the rights to their landholdings.

Consequences

Following a series of rebellions, the situation within Tōtōmi finally stabilized.  Active efforts by Ujizane to govern the province including the issuance of orders to creditors to relieve debts, the establishment of free markets, and the adjudication of water use rights contributed to the calm.  Meanwhile, owing to the rebellions in Tōtōmi, the Imagawa witnessed a dramatic loss of influence in neighboring Mikawa.  In the second month of 1564, Okudaira Sadayoshi (who had been aligned with the Imagawa for a long time) defected and, in the fifth month of 1566, the only remaining supporter of the Imagawa in Mikawa, Makino Narisada, the lord of Ushikubo Castle, affiliated with the Matsudaira clan.  Consequently, the Imagawa lost any vestiges of influence in Mikawa.

The continuation of the rebellion over a long period of time in Tōtōmi caused Takeda Shingen (an ally of Ujizane) to lose trust in Ujizane.  There is a theory that this raised doubts in regard to the ability of Ujizane to serve as a provincial lord.  According to this theory, Shingen’s mistrust of Ujizane bred by the Enshū Discord led to a deterioration of diplomatic relations between the Imagawa and Takeda clans, giving rise to the Yoshinobu Incident and the invasion of Suruga by the Takeda.

After the end of the Enshū Discord, Imagawa Ujizane continued to serve as a daimyō in Suruga and Tōtōmi provinces, but beginning in 1568, incurred an invasion of the territory of the Imagawa by Takeda Shingen and Tokugawa Ieyasu, eventually losing the territory.