ante diem xvii kalendas maias
- ludi Cereri continue (day 4)– games in honour of the grain goddess Ceres, instituted by/before 202 B.C.
- Fordicidia — an obvious fertility ritual in which a pregnant cow would be sacrificed to the earth goddess Tellus
- 421 B.C. — Peace of Nikias brings the first phase of the Peloponnesian war (a.k.a. the Archidamian War) to an end (by one reckoning)
- 69 A.D. — the forces of emperor wannabe Vitellius defeat the forces of emperor wannabe Otho
- 251 A.D. — Martyrdom of Maximus and Olympiades in Persia