1556: The Battle of Nagaragawa—The Death of Saitō Dōsan
Saitō Dōsan of Mino, whose favoritism toward his younger sons had alienated his heir Yoshitatsu, clashed with Yoshitatsu's much larger army at the Nagara River. Reinforcements from his son-in-law Oda Nobunaga arrived too late, and the badly outnumbered Dōsan was killed in battle. The man once feared as the 'Viper of Mino' for his own ruthless rise to power met an ironic end at the hands of his own son.
Events this year
Month 5
Saitō Dōsan fought his heir Yoshitatsu on the Nagara River and was killed. Oda Nobunaga's relief came too late, and Mino passed to Yoshitatsu.
See this battle in detail →Sources 岐阜市「［市］道三塚」／岐阜市「ナビ番号：315 常在寺」／岐阜県歴史資料館「斎藤義龍肖像」
Month 7
Over control of the Iwami silver mines, Amago Haruhisa's forces defeated the Mōri faction under Kikkawa Motoharu at Oshihara, inflicting heavy losses on the Mōri.
Sources 島根県教育委員会「石見銀山遺跡 大田市内の山城マップ」
Month 9
Oda Nobunaga beat Shibata Katsuie and Hayashi Hidesada, who had raised his brother Nobuyuki, on the plain of Inō, and secured his place within the Oda Danjōnojō house.
See this battle in detail →Sources 名古屋市「庄内学区（西区）の紹介」／Wikipedia「稲生の戦い」