On July 5, just before attack was to be launched, a conspiracy to topple the Taira clan was revealed through a betrayal by Yukitsuna TADA (the Shishigatani Incident).
攻撃直前の6月1日、多田行綱の密告により平氏打倒の陰謀が発覚した（鹿ケ谷の陰謀）。