Look up: Armilustrium

1. 
   Armilustrium
   Purification of the Armaments A military festival held annually on October 19-20th to celebrate the conclusion of the campaign season, during which captured arms were dedicated to Mars, and the standards purified.
   Found on http://www.roman-britain.org/military/mi
   
   
2. 
   Armilustrium
   The `Armilustrium` was a festival in honor of Mars, the god of war, celebrated on October 19. On this day the weapons of the soldiers were ritually purified and stored for winter. The army would be assembled and reviewed in the Circus Maximus, garlanded with flowers and the trumpets (tubae) would be played as part of the purification rites. The Romans gathered with their arms and armour on the Aventine Hill, and held a procession with torches and...
   Found on http://en.wikipedia.org/wiki/Armilustriu