Although Godaigo decided to lead a military uprising earlier than planned (Genko Incident), the bakufu started to arrest related people and moved large forces to suppress the revolt, so Godaigo eluded arrest by escaping Kyoto and joined his rebel army.
後醍醐は予定を早めて武装蜂起（元弘の変）に踏み切ったが、幕府は関係者の逮捕に着手するとともに、大軍を動員して鎮圧に乗り出し、後醍醐も逮捕されることを避けて京都を脱出し自ら叛乱軍に加わった。