ante diem v idus septembres
- ludi Romani (day 5)
- 490 B.C. — battle of Marathon (by one reckoning)
- 3 A.D. — Gaius Caesar, adoptive son/grandson of the emperor Augustus, is wounded at Artagira
- 9 A.D. — Quintilius Varus loses three legions (and his life) in the Battle of the Teutoburg Forest (a.k.a. the clades Variana)
- 1st century — martyrdom of Felix and Constantia
- 1850 — birth of Jane Ellen Harrison (author of Themis)