Ujiyasu HOJO requested help of Shingen TAKEDA (Harunobu TAKEDA entered into priesthood in 1559 and changed his name to Shingen TAKEDA), and responding to this request, Shingen invaded the northern Shinano area.
北条氏康は、同盟者の武田信玄（武田晴信が永禄2年に出家して改名）に援助を要請し、信玄はこれに応えて北信濃に侵攻。