Lifespan: Kōji 3 (1557) to 6/25 Genna 8 (1622)
Other Names: Hisachiyomaru (childhood) → Motokane → Motoyoshi → Juni (monk’s name)
Title: Deputy Governor of Kazusa
Clan: Yasuda (an illegitimate branch of the Daiei-Mōri)
Lord: Uesugi Kenshin → Uesugi Kagekatsu
Father: Yasuda Kagemoto
Siblings: Kagehiro, Akimoto, Yoshimoto
Adopted Children: Toshihiro
Yasuda Yoshimoto served as a bushō from the Sengoku to early Edo periods. He was a retainer of the Uesugi clan. Yoshimoto is counted among the Twenty-Five Bushō of the Uesugi. This was an elite group of bushō selected from among all of the bushō serving under Uesugi Kenshin.
As descendants of Daiei Hiromoto, the first-generation steward of the office of finances of the Kamakura bakufu, the Yasuda were an illegitimate branch of the Daiei-Mōri clan so in some accounts he is referred to under the surname of Mōri. To differentiate from Yasuda Nagahide of the Ōmi-Yasuda who was also a retainer of the Uesugi, Yoshimoto’s family is also referred to as the Mōri-Yasuda clan.
In 1557, Yoshimoto was born as the son of Yasuda Kagemoto at Yasuda Castle in the Kariwa District of Echigo. From his youth, he was engaged as a servant of Uesugi Kenshin and given the common name of Yakurō.
In 1578, the death of Uesugi Kenshin triggered a succession struggle between two of his adopted sons, Uesugi Kagekatsu and Uesugi Kagetora. This is known as the Otate Conflict. During this event, Yoshimoto joined his older brother, Yasuda Akimoto, to support Kagekatsu. Eventually, Kagekatsu prevailed and became the next head of the Uesugi clan. After the conflict, the recognition and rewards were monopolized by the Ueda, direct retainers of Kagekatsu. This triggered severe opposition from Shibata Shigeie and Horie Munechika (who initially supported Kagetora but switched his support to Kagekatsu through the efforts of Akimoto). Akimoto attempted to mediate between the two sides but failed and, bearing responsibility, took his own life so Yoshimoto inherited the headship of the clan. On 9/25 of Tenshō 8 (1580), he received official recognition of his rights to his territory and was further awarded the former territory of Horie Munechika.
From 1582, Yoshimoto participated in efforts to suppress a revolt by Shibata Shigeie over a period of several years. At the Battle of Hōjōbashi, while serving in the rear guard, he sustained injuries to one of his legs. This ailed him for the remainder of his life so he was given the nickname invoking his condition.
Service to the Toyotomi clan
In 1586, the Uesugi submitted to the Toyotomi clan. Yoshimoto excelled in internal affairs so, when Kagekatsu was away from his territory, he delegated governance to Yoshimoto. In 1592, during the Bunroku Campaign on the Korean Peninsula, Yoshimoto, together with Fujita Nobuyoshi, were assigned to guard Kasugayama Castle in Echigo. According to records prepared in Bunroku 3 (1594) by Izumisawa Hisahide, around this time, Yoshimoto’s fief was 2,474 koku.
In 1598, after the Uesugi clan was transferred to Aizu with a fief of 1,200,000 koku, Yoshimoto was ordered to defend Asaka and Nihonmatsu castles. At this time, his fief was 11,000 koku, and he was appointed along with Iwai Nobuyoshi and Ōishi Tsunamoto to serve as the three magistrates of Aizu. He served as the head of this group. Kagekatsu, while based on Fushimi Castle, ordered Yoshimoto to build Kōzashi Castle, manage the construction of roads and bridges, engage the services of rōnin, or wandering samurai, and manufacture armaments. Around this time, Yoshimoto developed friendly relations with Maeda Yoshimasu who also served as an official of the Uesugi clan.
Battle of Sekigahara to the Siege of Ōsaka
In 1600, Yoshimoto made preparations to defend against the Eastern Army led by Tokugawa Ieyasu planning to invade Aizu with the aim of subduing the Uesugi clan. Yoshimoto defended Komine Castle and, together with Shimazu Tadanao, led the first division at Kawagohara. While marching toward Aizu, Ieyasu received news that Ishida Mitsunari had launched a rebellion from Ōsaka Castle. He then held a war council on 7/25 in Oyama in Shimotsuke Province. At this meeting, known as the Oyama Deliberation, Ieyasu decided to return west toward Ōsaka to confront Mitsunari rather than continue north to subdue Uesugi Kagekatsu. On 9/15, the Eastern Army subsequently defeated the Western Army at the Battle of Sekigahara. In 1601, the territory of the Uesugi clan was reduced to 300,000 koku in Yonezawa in Dewa Province. At this time, Yoshimoto departed from Asaka and Nihonmatsu castles.
After moving to Yonezawa, Yoshimoto joined Naoe Kanetsugu and others to promote the development and subdivision of the town below the castle. At this time, Yoshimoto received a fief of 4,330 koku. In 1602, Kanetsugu sponsored a poetry event attended by Yoshimoto, Ōkuni Saneyori, Suibara Chikanori, Iwai Nobuyoshi, Kasuga Mototada, Maeda Toshikmasu, and others at the Kameoka-Monju Temple in Takahata in the Higashi-Okitama District of Dewa. The waka and Chinese poetry that were the subject of this event were dedicated in a compilation of works under the name of Naoe Kanetsugu and others. In 1612, Yoshimoto joined Kanetsugu, Chikanori, Nobuyoshi, Yamagishi Naoie, and Hirabayashi Masatsune to enact family rules with seventeen provisions.
In 1614, Yoshimoto deployed for the Winter Campaign of the Siege of Ōsaka. Initially, he was assigned to the first division, but based on the formations established by Kagekatsu, was moved to the second division to have a stronger general in place. This showed honor toward Suda Nagayoshi, the youthful commander of the first division while angering Yoshimoto, raising the motivation of each one of them while also preserving the fighting force of the second division under the experienced Yoshimoto. At the Battle of Shigino, the Uesugi were initially in a superior position but gradually pushed back by the larger army commanded by Ōno Harufusa, causing the Suda division to fall into disarray. Serving in the rear guard, Suibara Chikanori led an arquebus battalion to halt the progress of the Ōno division while the Yasuda division charged with 500 soldiers to successfully repel them.
After the battle, those bushō who served valorously received written commendations and rewards from Tokugawa Ieyasu and Tokugawa Hidetada, one after another, but Yoshimoto did not receive any recognition. This is deemed owing to a deterioration in relations following the Battle of Sekigahara with Naoe Kanetsugu who was in charge of diplomatic relations with the Tokugawa clan. In this regard, Yoshimoto noted “I do not believe the lack of recognition to be a sign of dishonor. I fought for my lord not for the shōgun or prior shōgun.” This implicitly showed contempt for Kanetsugu who was pleased to receive commendations for guiding forces in battle against the Tokugawa at the Battle of Sekigahara and from Hidetada at the Siege of Ōsaka. Upon hearing this, Kanetsugu was said to have no reply.
On 6/25 of Genna 8 (1622), he died at the age of sixty-six. The headship of the clan was inherited by Yasuda Toshihiro who was adopted from the Nawa clan.