ante diem v idus martias
- Festival of Mars (day 11)
- 222 A.D. — murder of the emperor Elagabalus
- ca. 263 A.D. — martyrdom of Heraclius
- ca. 300 A.D. — martyrdom of Thalus
- ca. 300 A.D. — martyrdom of Trophimus
- 1903 — birth of Ronald Syme (The Roman Revolution, among other seminal works)