However, after conquering Suruga, TAKEDA remade the Koso Alliance (an alliance between the Takeda clan in Kai Province and the Hojo clan in Sagami Province) and on October, 1571, he invaded Totomi and Mikawa Provinces in a large scale, which resulted in the decisive confrontation with the Oda and Tokugawa allied forces.
が、駿河を平定した武田は甲相同盟を回復すると、元亀2年（1571年）10月には大規模な遠江・三河侵攻を行い織田・徳川連合との対立が決定的となる。