En'ō (延応) was a Japanese era name (年号, nengō, lit. "year name") after Ryakunin and before Ninji. This period spanned the years from February 1239 to July 1240.[1] The reigning emperor was Shijō-tennō (四条天皇).[2]
Change of era
1239En'ō gannen (延応元年): The era name was changed to mark an event or a number of events. The previous era ended and a new one commenced in Ryakunin 2.
Events of the En'ō Era
1239 (En'ō 1, 1st month): The Daijo daijin Kujō Yoshihira (九条 良平) retired from worldly concerns, taking the tonsure of a Buddhist priest.[3]