ante diem xiii kalendas maias

ludi Cereri (day 8)-- games in honour of the grain goddess Ceres, instituted by/before 202 B.C.

Cerealia -- the actual date of the Cerealia is uncertain, but it 'reenacted' Ceres' search for her daughter Proserpina, with apparently all participants and spectators dressed in white.

69 A.D. -- Vitellius is recognized as emperor by the senate in Rome

... we also note today is the commemoration of an (undated) Roman soldier saint Expeditus