ante diem iv kalendas martias

Equirria -- the first of two days of horse racing (the second was on March 14) dedicated to Mars; the reasons are obscure, but probably have something to do with preparing horses for the upcoming campaigning season

116 A.D. -- supplicatio pro salute Traiani (day 2)

1874 -- birth of F.M. Cornford (author of Before and After Socrates, among several other works)