ante diem xiii kalendas apriles

Festival of Mars (day 20)

Quinquatrus (day 2) -- second day of a five-day festival (although the name originally came from the fact that it came five days after the Ides, apparently) sacred to Mars but also somehow connected to Minerva; it was also apparently a 'school holiday', so no doubt we'll soon be reading about how the Romans invented Spring Break

43 B.C. -- Birth of Ovid (by one reckoning)

268 A.D. -- assassination of Gallienus