Wikipedia
Agonalia
An Agonalia or Agonia was an obscure archaic religious observance celebrated in ancient Rome several times a year, in honor of various divinities. Its institution, like that of other religious rites and ceremonies, was attributed to Numa Pompilius, the semi-legendary second king of Rome. Ancient calendars indicate that it was celebrated regularly on January 9, May 21, and December 11.
A festival called Agonia or Agonium Martiale, in honor of Mars, was celebrated March 17, the same day as the Liberalia, during a prolonged "war festival" that marked the beginning of the season for military campaigning and agriculture.