Mogami Yoshiaki

was a daimyō of the Yamagata Domain in Dewa Province, in the late Sengoku and early Edo periods. He was known as the "Fox of Dewa".

His younger sister, Yoshihime, later became the wife of Date Terumune and gave birth to Masamune, making him the uncle of Date Masamune.

It was recorded in historical documents that his height was over 180 cm.

Biography Early life Mogami Yoshiaki was born on the first day of the first month of the Tenbun era (1546) to his father, Yoshimori, However, in the Komyoji version of the Mogami clan's tree document(compiled in 1746), Nakano-dono appeared as the younger brother of Mogami Yoshimitsu. Based on this material, professor Kenji Matsuo did not dismiss the possibility the existence of Yoshiaki's younger brother who disputed the position inheritance of Yoshiaki.

In 1570, at the age of 25, Yoshiaki inherited the clan leadership from his father and set upon his goal of reviving the hereditary position of his clan as Oshu Tandai (Overseer of Dewa Province, the areas of which encompass modern-day Akita and Yamagata prefectures). He expanded not only into the northern and western parts of Yamagata Prefecture, but also into the southern part of Akita Prefecture.

Unification of Dewa province

In 1571, Mogami Yoshiaki officially became the head of the Mogami clan. Yoshiaki married a woman from the Osaki clan of the Mutsu province, who was his relative. When Date later attacked the Osaki clan the relationship between Yoshimitsu and Date Masamune deteriorated.

In 1586, Yoshiaki fought against Onodera Yoshimichi. Yoshiaki's eldest son, Mogami Yoshiyasu and Tateoka Mitsushige succeeded in defeating the Onodera reinforcements. In October, Yoshiaki crossed the Rokuji Highway and invaded Shōnai in an effort to reinforce Tōzenji Yoshinaga, lord of Tozenji Castle, against the attack of his enemy, Daihōji Yoshioki. Yoshioki was defeated in battle the same month and committed suicide, causing the Daihōji clan to go extinct. In 1587, he succeeded in taking control of Shonai (western Yamagata prefecture). However, the next year, his army was defeated and routed by Honjō Shigenaga, a retainer of Uesugi Kagekatsu, in Battle of Jugorihara. This defeat, along with the fact that his nephew, Date Masamune, was also expanding his own ambitions at the same time, and he was targeting domains within the Mogami clan, prompted Yoshiaki to give up Shōnai and move his focus towards the Date clan.

Incident of Yoshiaki daughter In 1591, after the Siege of Odawara, he participated in the Kunohe Rebellion. During this time, Toyotomi Hidetsugu, who had been chosen as Toyotomi Hideyoshi's successor, fell in love with Yoshiaki's daughter, Komahime, and married her, and Yoshiaki became an important Toyotomi daimyo as because of his relation to the Toyotomi clan. In 1591, Yoshiaki was allowed to use the surname of Toyotomi, and usually called himself Hashiba Yoshiaki. Although he did not end up sailing to Korea during the Bunroku Invasion, in 1592, he went to Nagoya Castle in Hizen with 500 of his retainers to prepare for passage to Korea.

Sekigahara Campaign

In 1600, when the Sekigahara campaign broke out between Ieyasu and his enemies led by Ishida Mitsunari, Ieyasu entrusted Yoshiaki with command of northern Oshu. On April 19, Ieyasu instructed the Nanbu, Onodera, and Akita clans to obey Yoshiaki's command,

The Uesugi forces which numbered more than 20,000, were invaded from the south by the main force commanded by Naoe Kanetsugu via the Kitsunegoe Highway, and from the west by the Shonai area. Because the difference in military strength between the Mogami forces and the Uesugi forces were huge, Yoshiaki requested reinforcements from Date Masamune. The Uesugi forces were defeated in the attack on Kaminoyama Castle, and fled back to Yonezawa in disarray. In the 15 days of ineffective siege against the Hasedō Castle, the Uesugi troops cannot capture it from the persistent Mogami forces. In the final phase of this siege, the Uesugi forces launched another all-out attack on Hasedō Castle, but with the help of Date's reinforcements, they were able to hold out against the large Uesugi forces. In the end, when information came in that Tokugawa Ieyasu emerged victorious in the main Sekigahara battle, The uesugi forces under Kanetsugu began to withdraw from Hasedō Castle. Switching positions, Yoshiaki began to pursue them, but Kanetsugu himself concentrated his riflemen to defend his retreating army, and managed to withdraw safely back to Yonezawa. After the campaign ended, the Mogami clan was rewarded with an increase in size from 200,000 to 570,000 koku for their domain in return for their loyalty to the Eastern army during the war. This made the Yamagata domain the fifth largest in Japan at the time, excluding the land held by Tokugawa. On May 11, Ieyasu, who had established his hegemony over the Toyotomi government, visited the Imperial Palace to receive an audience with the Emperor. He was accompanied by Mogami Yoshiaki as well as Mori Tadamasa, who had been instrumental in the attack on the Sanada clan, and Ii Naomasa, who had led the vanguard in the Battle of Sekigahara, and Oda Nagamasu. Yamagata maintains the Mogami Yoshiaki Historical Museum, just outside the rebuilt Great Eastern Gate of Yamagata Castle, which displays his helmet, battle command baton and other implements he actually used.

It was reported that during his reign as Mogami clan's head not a single local uprising occurred within the territories of Mogami clan.

Notable vassals Tateoka Mitsushige Sakenobe Hidetsuna Eguchi Gohei Satomi Minbu Ujiie Sadanao Ujiie Munemori Shimura Akiyasu

Appendix Footnotes