In the generation of Yoshimichi ISSHIKI, Yoshimichi was killed in 1579 as a result of the invasion of an army led by Yusai HOSOKAWA, as ordered by Nobunaga ODA, and thereafter Yoshimichi's son Yoshisada ISSHIKI and Yoshimichi's younger brother, Yoshikiyo ISSHIKI tried hard to fight against the Hosokawa army; however, they were killed in 1582, and this resulted in the complete downfall of the Isshiki clan in Tango.
そして一色義道の時代には、織田信長の命令を受けた細川幽斎軍の侵攻に遭って義道は1579年に殺され、その後を義道の子の一色義定や、弟の一色義清も継いで細川軍と懸命に戦ったが、最終的には1582年に両者も殺されて、丹後における一色氏は完全に滅亡してしまった。