1583: The Battle of Shizugatake—Hideyoshi Defeats Shibata Katsuie
Hashiba Hideyoshi, at odds with Shibata Katsuie over the succession to Oda Nobunaga and Katsuie's backing of Oda Nobutaka, clashed with Katsuie's army at Shizugatake in Ōmi. When Maeda Toshiie's forces withdrew from the Shibata line, Katsuie's army collapsed entirely; he retreated to his base at Kitanoshō Castle and took his own life. Hideyoshi thereby effectively secured his position as Nobunaga's successor.
Events this year
6/11
The armies of Hashiba Hideyoshi and Shibata Katsuie fought around Shizugatake in Ika District, Ōmi Province, and the Shibata army was defeated.
See this battle in detail →Sources Wikipedia「賤ヶ岳の戦い」／長浜市「賤ヶ岳合戦エリア」
6/14
After retreating from Shizugatake, Shibata Katsuie was attacked by Hashiba forces at Kitanoshō Castle and took his own life with Lady Oichi.
See this battle in detail →Sources Wikipedia「賤ヶ岳の戦い」
Month 9
Hashiba Hideyoshi began constructing Osaka Castle on the former site of Ishiyama Hongan-ji as a political and military base for unifying the realm.
Sources 大阪市「大坂城跡（天守閣）・旧大阪市立博物館」
Oda Nobutaka, who had allied with Shibata Katsuie against Hashiba Hideyoshi and Oda Nobukatsu, was isolated after the defeats at Shizugatake and Kitanoshō and took his own life at Ōmidōji in Noma, Owari.
Sources 愛知県公文書館「愛知の歴史資料」／滋賀県「賤ヶ岳の戦いから小牧・長久手の戦いへ」