In the Roman calendar, March was sacred to Mars. On the 21st the “jumping priests,” or Salii began the festival with a purification of the sacred trumpets that the Romans carried off to war. They marched to the Regia taking the bronze Ancilia, the sacred shield that had fallen down from heaven, and its 11 copies and for 3 days they danced through the streets singing hymns so ancient that Cicero couldn’t understand them. Each night, they would stop at a place to be feasted before starting up again the next day.
This festival would end on March 24 when they would return to the Regia and return the shields. That date was originally the new year because it was the start of the growing and campaign season.