The view that this incident occurred on the 18th is taken by "Shinsengumi Shimatsuki" and "Shinsengumi Ibun," but there is also an opinion that there was no rainfall during the night of 18th and that the incident occurred on 16th when there was rainfall; there is no fixed view yet.
18日説は『新選組始末記』『新選組遺聞』が採るものであるが、18日夜には降雨がなく、降雨があったのは16日であるとして、16日説を推す意見もあり、いまだ定説はない。