1555: Battle of Itsukushima
Mōri Motonari defeated Sue Harukata at Itsukushima and greatly expanded his power in the Chūgoku region. The victory hastened the decline of the Ōuchi and the rise of the Mōri.
Events this year
Month 8
Takeda Harunobu and Nagao Kagetora faced each other across the Sai River for a long time and came to terms through Imagawa Yoshimoto. No decisive battle was fought.
See this battle in detail →Sources 長野市「川中島古戦場史跡公園」／ながの観光net「川中島の戦い 史跡ガイド」
Month 10
Mōri Motonari crossed to Itsukushima, struck Sue Harukata's camp and broke it. The Ōuchi lost their grip on power and the Mōri rose in the Chūgoku region.
See this battle in detail →Sources 宮島観光協会「厳島合戦」／広島県「戦国大名とひろしま～毛利元就～」／廿日市市「宮島物知り図鑑：宮島ゆかりの人々」
After defeating Sue Harukata at Itsukushima, Mōri Motonari began a major invasion of the Ōuchi territories in Suō and Nagato. The campaign continued until 1557 and led to the fall of the Ōuchi and Mōri control of the two provinces.
Sources 山口県「さらば!! 西国一の大名・大内氏『最後の当主』大内義長」
Umechiyoōmaru underwent a coming-of-age ceremony at Kasai Castle under the supervision of Hōjō Ujiyasu and received the character "Yoshi" from Shogun Ashikaga Yoshiteru.
Sources 葛飾区「葛飾区史 第2章 葛飾の成り立ち」
Merchant Luis de Almeida established an orphanage in Bungo. With the support of Ōtomo Yoshishige, the institution took in children abandoned due to poverty.
Sources 大分市「大友宗麟とその時代」
Asakura Sōteki marched to battle against the Kaga Ikkō-ikki as supreme commander but fell ill in his encampment and died at the age of 79, depriving the Asakura clan of a longtime senior retainer.
Sources 福井県「福井の戦国 歴史秘話＜第9号＞」