In 1578, when Kenshin UESUGI died of illness in Echigo, Otate War broke out between the two adopted sons of Kenshin, Kagetora UESUGI (formerly Saburo HOJO) and Kagekatsu UESUGI (Kenshin's nephew) over the succession to family headship.
翌天正6年（1578年）、越後で上杉謙信が病死すると、謙信の二人の養子である上杉景虎（旧名・北条三郎）と上杉景勝（謙信の甥）との間で家督を巡り御館の乱が起こる。