Miyoshi Motonaga served as a bushō in Awa Province during the Sengoku period.  Motonaga received one of the characters in his name from Hosokawa Harumoto, whom he served.  His father was likely Miyoshi Nagahide, or, Motonaga may have been the son of Miyoshi Yukinaga, who is otherwise considered his grandfather.  Nagahide was the designated successor of Yukinaga, but soon died in battle, so Yukinaga may have raised him as an adopted child of Nagahide.

In 1520, Yukinaga, owing to his position as the commander-in-chief of the Miyoshi clan, was executed after losing in battle to Hosokawa Takakuni.  Nagahide had preceded him in death, so Motonaga became the new head of the clan.  However, rather than mount a counterattack against Takakuni, Motonaga joined Hosokawa Rokurō, the orphan of Hosokawa Sumimoto (Yukinaga’s former lord) in Awa, under reduced circumstances.

After a falling out with Ashikaga Yoshitane, who aspired to reclaim his position as shōgun, Takakuni endeavored to solidify his dictatorial administration by installing Ashikaga Yoshiharu as the new shōgun.  In the seventh month of 1526, he revealed his true intentions by executing Kōzai Motomori on the basis of slander by Hosokawa Tadakata.  The unwarranted killing triggered a rebellion by Motomori’s two older brothers, Hatano Tanemichi and Yanagimoto Kataharu.  The inability of Takakuni to suppress them showed the weakness of the military capabilities of his administration.

This situation created an opportunity for Motonaga to raise arms in Awa in the tenth month of the same year.  Backing Ashikaga Yoshitsuna (Yoshiharu’s brother), Motonaga supported his lord, Hosokawa Rokurō, to challenge Takakuni’s army, marching to the Kinai Region.  After converging with the rebel army under the Hatano clan, the combined forces clashed with the bakufu army (allied forces of Takakuni and Yoshiharu) and defeated them at the Battle of Katsurakawara in the third month of 1527.  The rebel forces chased down the bakufu army to Ōmi Province, turning the tables on Takakuni’s administration.

Motonaga then contributed to the establishment of the Sakai kubō as an alternative to Takakuni’s administration which had lost its ability to function owing to their flight to Ōmi.  Takakuni aimed to expel the supporters of the Sakai kubō by leveraging additional forces contributed by Rokkaku Sadayori and Asakura Norikage (Sōteki); however, on 11/19 of 1527, Motonaga repelled an attack by Takakuni’s army at the Jōsen Temple near the Katsura River.  This helped significantly to solidify the newly established governance of Hosokawa Rokurō in the Kinai.

Retreat and return to the Kinai

In the seventh month of 1528, Motonaga was appointed the deputy military governor of Yamashiro for his prior contributions.  In 1529, Motonaga experienced deteriorating relations with his new colleague, Yanagimoto Kataharu, so he took refuge in Awa.  During this period, Takakuni reconstituted his army, acquiring additional troops from Kitabatake Harutomo (his son-in-law from Ise Province) and Uragami Muramune (the deputy military governor of Harima Province) to hold territory for purposes of an assault on the capital, and achieved a series of victories in battles across Harima.  Kataharu was dispatched to challenge Takakuni’s army in Harima, but owing to his sudden death in the sixth month of 1530 (possibly an assassination), toward late summer the allied forces of Takakuni and Muramune were able to invade Settsu Province.  In the absence of Motonaga, the situation for supporters of the Sakai kubō dimmed with retainers such as Yakushiji Kunimori surrendering to Takakuni’s forces.

In the second month of 1531, Motonaga responded to urgent appeals from Hosokawa Rokurō by returning, but the circumstances were dire.  His men endured vigorous attacks by the allied forces of Takakuni and Muramune across Harima.  Kizawa Nagamasa, a supporter of the Sakai kubō from Kawachi Province, abandoned the defense of Kyōto and withdrew, enabling Takakuni’s army to gain control of the capital.  Takakuni’s spirited forces advanced into the southern portion of Settsu intent on eliminating the Sakai kubō, whereupon Motonaga received an additional 8,000 men from Awa, blunting the vanguard of Takakuni’s army.  However, even with the reinforcements, over one-half of the military forces were assigned to protect Ashikaga Yoshitsuna in Sakai, while a lesser number were dedicated to confronting Takakuni’s forces, posing a major test of Motonaga’s abilities.  Then, at the Battle of Nakajima, the opposing armies deployed archery units to fight for days without a victor, leading to a stalemate that enabled Motonaga to halt the momentum of Takakuni’s army.  In the summer of 1531, Akamatsu Masasuke arrived under the pretext of serving as the rear-guard for Takakuni’s army, whereas, in fact, he had colluded in advance with the Miyoshi to launch a devastating pincer attack against the allied forces of Takakuni and Muramune, an event known as the Collapse at Daimotsu.

Confrontation with his lord

The supporters of Ashikaga Yoshitsuna, the Sakai kubō, attained their objective of defeating their arch-enemy, Hosokawa Takakuni.  This sense of achievement, however, soon yielded to internal discord in regard to the policies going forward.  If Ashikaga Yoshiharu was stripped of his current title as shōgun and replaced with Yoshitsuna, then Hosokawa Rokurō could seek official recognition of the bakufu based in Sakai.  Instead, he aimed for a reconciliation with Yoshiharu.

Motonaga, along with Hatakeyama Yoshitaka (Rokurō’s older brother-in-law from Kawachi Province), staunchly opposed this decision by Rokurō, which represented an abandonment of the Sakai bakufu that had been established with great effort.  Rokurō, however, refused to listen, creating a divide between their respective positions.  The great success achieved on the battlefield headed toward catastrophe as Rokurō gradually began to view them as a threat.  Meanwhile, operating behind the scenes were Kizawa Nagamasa, who sought a desirable position as an associate of Rokurō, and Miyoshi Masanaga (Motonaga’s uncle), who desired Motonaga to lose influence, serving to deepen the chasm.

Motonaga himself committed an error.  On 1/22 of 1532,  Motonaga led forces from Awa to eliminate Yanagimoto Jinjirō (the son of Kataharu) who had taken refuge in the Sanjō Castle in Kyōto.  Fearing retribution from Rokurō, he entered the priesthood and adopted the name of Kaiun.  Despite mediation by Hosokawa Mochitaka (Rokurō’s cousin serving as the military governor of Awa), Motonaga was not able to restore relations with Rokurō so that the relationship between the lord and his servant further deteriorated.

Finally, owing to the threat to his position posed by Nagamasa, Motonaga colluded with Hatakaeyama Yoshitaka (Nagamasa’s master who also feared being usurped by Nagamasa).  Motonaga supported the elimination of Nagamasa by Yoshitaka, so, in the eighth month of 1532, their forces surrounded Nagamasa’s base at Iimoriyama Castle.  Within only two months from the decimation of Takakuni, the faction supporting the Sakai kubō contended with internal differences.  Rokurō attempted to support Nagamasa, requesting withdrawal of the soldiers, whereupon Motonaga complied.  However, based on a continuing fear of Nagamasa’s ambition, in the fifth month of 1533, Yoshitaka once again surrounded Iimoriyama Castle.  Motonaga later came as a reinforcement.  Rokurō tried to support Nagamasa again, but the forces refused to withdraw, sealing the fate of Nagamasa.

The final period

On 6/15 of 1533, the final day of the campaign arrived. The prolonged siege aimed at the elimination of Nagamasa subjected the forces encircling the castle to a surprise attack from behind by several tens of thousands of warrior monks from the Ikkō-ikki religious group.  Their forces were quickly scattered, with Motonaga himself barely escaping to the Kenpon Temple in Sakai, affiliated with the Hokke (Nichiren) sect.  Meanwhile, Yoshitaka killed himself following relentless pursuit by the Ikkō-ikki army.

Rokurō and Nagamasa knew it would be impossible to expel the forces laying siege to the castle with their own army, so they leveraged the confrontation between adherents of the Ikkō and Hokke sects.  With the consent of the Yamashina-Hongan Temple, they requested support from the Ikkō-ikki army.  From the perspective of the Ikkō-ikki army, the elimination of the enemies of Buddhism was more important than scattering the army that was encircling Iimoriyama Castle.  The warrior monks sought to eliminate Motonaga because he was regarded as a protector of the Hokke sect, a rival of their Ikkō sect.  Yoshitaka was killed simply as a result of being caught-up in the situation.

The Ikkō-ikki army surrounding the Kenpon Temple swelled to tens of thousands of forces, posing a challenge for Motonaga to help Ashikaga Yoshitsuna escape.  Having been shunned by his lord and overwhelmingly defeated after the surprise attack, Motonaga committed seppuku, ending his life in despair.  Despite his regretful ending, his sons, including Miyoshi Nagayoshi, Miyoshi Jikkyū, Atagi Fuyuyasu, and Sogō Kazumasa became infamous warriors.  Through them, the Miyoshi clan thrived and, in their peak years, exercised control over the Kinai.  Twenty years later, Nagayoshi built a memorial to his father at the Nanshū Temple in Sakai.