Obata Kagenori

A military strategist in the early Edo period and the founder of the Koshu-ryu school of military tactics. He was the third son of Takeda retainer Matabei Masamori (1534-82), commonly known as Magoshichiro or Kanbei, and his name was Tsunao, later changed to Kagenori, and he went by the name Michigyu. In 1582 (Tensho 10), when he was four years old, the Takeda clan was destroyed and the Obata clan served the Ii clan of Enshu, but his older brother Masatada served Tokugawa Ieyasu, and through this connection, at the age of 11, he became a servant of Hidetada, who was seven years old at the time. He retired from service at the age of 24 in 1695 (4th year of Bunroku), and travelled around the country aspiring to become a military strategist. In 1600 (5th year of Keicho), he served under Ii Naomasa at the Battle of Sekigahara, where he distinguished himself, but he became a ronin again, and in 1707, he received the Itto-ryu inka from Ono Tadaaki in Edo, and taught in Kyoto. In 1714, during the Winter Siege of Osaka, he joined Maeda Toshitsune, and is said to have achieved military success by attacking the Sanada fort. During the Summer Siege, he conspired with Itakura Katsushige, and accepted an invitation from Ono Harunaga under false pretenses to enter Osaka Castle, where he explored the castle and escaped just before it fell, reporting it to the Tokugawa side. After the war, he was allowed to return to the Tokugawa clan with a fief of 500 koku, and in 1602 (Kan'ei 9), he was promoted to Oshiban, with 1,500 koku in Sagami, Koshu, etc. During this time, he learned castle capture from Hayakawa Yukitoyo, a surviving retainer of the Takeda clan, and traditional military tactics from Okamoto Hansuke, Akazawa Tarozaemon, Masuda Hidenari, and others. With the help of his trusted disciples Sugiyama Hachizo Morimasa and Murakami Shojiro Masanobu, he solidified his foundation in military tactics and compiled the fundamental textbook "Kōyō Gunkan" with additional editions, establishing himself as a leading scholar. Towards the end of the Kan'ei period (1624-1644), his fame further increased, and over 2,000 people, including feudal lords such as Hosokawa Mitsunao (Kumamoto), Matsudaira Terutsuna (Kawagoe), and Asano Nagaharu (Miyoshi), visited his school, with 33 inka disciples. Among them, Hojo Ujinaga and Yamaga Sokou were the most famous, and they furthered their master's learning and became the founders of their own schools.

[Ichiro Watanabe]

“Hisao Ishioka, History of Japanese Military Law Volume 1” (1972, Yuzankaku Publishing)” ▽ “Hisao Ishioka, “The Life of a Military Soldier” (1981, Yuzankaku Publishing)”

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

江戸初期の兵法学者、甲州流兵法の始祖。武田の家士又兵衛昌盛(まさもり)（1534―82）の第3子、通称孫七郎または勘兵衛、名は縄尚（直）(つななお)のち景憲と改め、道牛と号した。1582年（天正10）4歳のとき武田家が滅亡し、小幡一族は遠州井伊氏に仕えたが、兄昌忠は徳川家康に仕え、その縁で11歳のとき当時7歳の秀忠(ひでただ)の侍童となった。95年（文禄4）24歳のとき致仕し、兵法家を志して諸国を遍歴し、1600年（慶長5）関ヶ原の戦いに井伊直政の麾下(きか)に属して功を立てたが、ふたたび浪人して、07年には江戸の小野忠明(ただあき)より一刀流の印可を受け、京都で教授した。14年大坂冬の陣には前田利常(としつね)の手に加わり、真田(さなだ)の砦(とりで)を攻めて軍功があったという。夏の陣には、板倉勝重(かつしげ)と通じ、偽って大野治長(はるなが)の招きに応じて大坂城に入り、城内を探索して陥落直前に脱出、徳川方に通報した。戦後、徳川家への復帰を許されて500石を知行(ちぎょう)し、32年（寛永9）には御使番に進み、相模(さがみ)、甲州などで1500石を領した。この間、城取りを武田の遺臣早川幸豊(ゆきとよ)の門に、また古伝の軍配兵法を岡本半助(はんすけ)、赤沢太郎左衛門、益田秀成らに学び、また腹心の門人杉山八蔵盛政、村上庄次郎昌宣(まさのぶ)の協力によって兵法学の基盤を固め、根本伝書『甲陽軍鑑』を増補集成して一流を樹立した。寛永(かんえい)（1624～44）末年には名声も一段と高まり、細川光尚（熊本）、松平輝綱(てるつな)（川越）、浅野長治(ながはる)（三次(みよし)）などの諸大名をはじめ、その門に遊ぶ者2000余人に及び、印可門人は33名を数えた。なかでも北条氏長(うじなが)、山鹿素行(やまがそこう)が有名で、師の学を発展させて、それぞれ一流の祖となった。

［渡邉一郎］

『石岡久夫著『日本兵法史　上』（1972・雄山閣出版）』▽『石岡久夫著『兵法者の生活』（1981・雄山閣出版）』

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