The day after Samhain

A century later, Pope Gregory III (731–741) wasn’t comfortable with the connection with an occult holiday, so he moved All Saints’ Day to November 1.

However, that put it the day after Samhain, a Celtic day of the dead much like Lemuria. Devout Irish Christians recognized the problem and chose not to celebrate All Hallows Day on November 1, instead observing it on April 20.

However, elsewhere November 1 became All Saints' Day and Samhain turned into All Hallows’ Eve – Halloween.