1615: The Summer Siege of Ōsaka—The Fall of the Toyotomi and the One-Castle-per-Domain Edict
With its outer moats filled in under the terms of the winter truce, Ōsaka Castle stood nearly defenseless, and the Toyotomi forces sought their only chance in open battle against the Tokugawa army, but were defeated. In May, Hideyori and his mother Yodo-dono took their own lives, ending the main Toyotomi line. The shogunate soon issued the One-Castle-per-Domain edict and the Buke Shohatto code, tightly regulating daimyo fortifications and armaments and bringing the age of the Sengoku warring states to its final close.
Events this year
5/6
At Dōmyōji and Tamateyama in Kawachi, Gotō Mototsugu engaged the Tokugawa forces. At Yao and Wakae, Kimura Shigenari and Chōsokabe Morichika also clashed with them. Both Mototsugu and Shigenari fell in battle.
See this battle in detail →Sources 柏原市「玉手山と大坂夏の陣」／八尾市「三一巻 続・河内名所図会を訪ねて(3) 大坂夏の陣と八尾」
5/8
Osaka Castle fell, and Toyotomi Hideyori and Yodo-dono died by suicide, bringing the main Toyotomi house to an end.
See this battle in detail →Sources 国立公文書館「大坂冬の陣・夏の陣」
7/7
Tokugawa Hidetada assembled the daimyo at Fushimi Castle and promulgated the Laws for the Military Houses, setting principles for shogunate control over the daimyo.