In 1561, although Kagetora NAGAO's attempt to fully conquer Odawara-jo Castle in order to rescue Fujiuji and put down the Hojo clan by sending a large force of over hundred thousand soldiers including Kanto Kanrei Norimasa UESUGI and Kanpaku (chief advisor to the Emperor) Sakihisa KONOE to Kanto region was unsuccessful, he brought most of Kanto region under his control by completely conquering Koga Imperial Palace and banishing a puppet of the Hojo clan Yoshiuji ASHIKAGA who barricaded himself in the Imperial Palace (Fujiuji entered Koga instead).
藤氏救援と北条討伐のため、永禄4年（1561年）、関東管領上杉憲政・関白近衛前久を擁して10万余の大軍で関東に出兵した長尾景虎は小田原城の完全攻略には失敗したものの、古河御所は完全に制圧し、御所に籠る北条氏傀儡の足利義氏を追放する（代って藤氏が古河に入った）など、関東の大半を制した。