The Ides of March is a Roman calendar day that generally corresponds to March 15 in the modern calendar. The Ides of March is also the official day of Julius Caesar's assassination and the Roman Republic's Anna Perenna festival.
The Romans conveyed dates in relation to the lunar phases, which they identified as Kalends, Nones and Ides. The Romans initially used the Ides of March to mark the first full moon of a new year. Ides can either take place on the 13th or 15th day of the month. Kalends and Nones take place within the first week of the month.