Mogami clan

A prestigious samurai family that is said to be the first branch of the Shiba clan of the Ashikaga clan. It began in 1356 (Shohei 11, Enbun 1) when Kaneyori, the second son of Oshu Tandai Shiba (Osaki) Iekane, entered Mogami District, Dewa Province (Yamagata Prefecture) and built Yamagata Castle. His descendants later called themselves the Mogami clan and boasted great power as Ushu Tandai, but there are many unknowns about the middle period, and due to family conflicts and the rise of powerful clans, the Tandai title became nothing more than an empty title. When Yoshiaki took over at the end of the 16th century, he wiped out the family and strengthened his ruling power, advanced his army towards the Shonai area, and finally became a great daimyo who owned most of present-day Yamagata Prefecture. At the Battle of Sekigahara, the Tokugawa clan was granted 570,000 koku in Yamagata. However, because the territorial system was immature, internal conflict intensified after Yoshimitsu's death. Finally, in 1622 (Genwa 8), the shogunate confiscated Mogami Yoshitoshi's 570,000 koku of land, transferred him to Omori in Omi (Higashiomi City, Shiga Prefecture), and gave him 10,000 koku (5,000 koku in Mikawa). In 1631 (Kan'ei 8), because his heir Yoshitomo was still a child, he was further reduced by 5,000 koku and made a takaie.

[Keinon Honda]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

足利(あしかが)一門の斯波(しば)氏の一流と称する名門武家。1356年（正平11・延文1）奥州探題(おうしゅうたんだい)斯波（大崎）家兼(いえかね)の二男兼頼(かねより)が出羽国(でわのくに)（山形県）最上郡に入部し、山形城を築いたのに始まる。その子孫がのちに最上氏を称し、羽州探題(うしゅうたんだい)として権勢を誇ったが、中ごろは不明な点が多く、一族の対立や豪族の台頭などにより、探題は空名にすぎなくなっていた。16世紀末に義光(よしあき)が継ぐと、一族を掃討して支配権力を強め、庄内(しょうない)方面に軍を進め、ついに現山形県の大半を領有する大大名に躍進した。関ヶ原の戦いでは徳川氏につき山形57万石に封ぜられた。しかしその領国体制は未熟であったため、義光の死後内紛が激化した。ついに1622年（元和8）幕府は最上義俊(よしとし)の所領57万石を没収し、近江(おうみ)大森（滋賀県東近江市）に転封して1万石（5000石は三河国内）を与えた。1631年（寛永8）嗣子(しし)義智(よしさと)幼少のためさらに5000石を削減され高家(こうけ)とされた。

［誉田慶恩］

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