Ides (of March or whenever)

Reverse side of a coin issued by Caesar's assassin Brutus in the fall of 42 BC,
with the abbreviation EID MAR (Ides of March) under a "cap of freedom" between two daggers

Today is the "Ides of March" (Latin: Idus Martii or Idus Martiae) but it is not a date limited to the month of March, although William Shakespeare's Julius Caesar has fixed that particular Ides in our culture. Shakespeare, like playwrights and filmmakers of our time, used history for his stories, and you shouldn't learn your history only from the arts.

In his play, a soothsayer makes the prophecy that Caesar needs to "Beware the Ides of March." It turns out to be true as a few idealistic Romans decide to win Rome back for the people by killing Caesar. Even his friend, Brutus, gets in on the multiple stabbings and is asked "Et tu Brute?" by the Emperor.

But that is only partially true to history. The history is actually as interesting as the fiction. For example, there was a soothsayer named Spurinna whose divination foretold (the bad omen was supposedly a bull without a heart) that had him tell Caesar to beware for the next 30 days. Like soothsayers throughout history and into today, the mysticism was mixed with some careful assessment of the real world. The 30 days would end with March 18 and Caesar was going to embark on a multi-year military campaign that would take him away from Rome, any assassination would probably occur before he left.

The Death of Caesar (1798) by Vincenzo Camuccini

The ancient Romans did count the days of the month as we do - sequentially from the first through the last day. They counted back from three fixed points of the month. It varied a bit by the month, but the Nones was the 5th or 7th, the Ides (13th or 15th), and the Kalends was the first of the following month).

The Ides occurred near the midpoint, on the 13th for most months, but on the 15th for March, May, July, and October.

Being that the Roman calendar was a lunar one, the Ides were supposed to be determined by the full moon. Originally, the Ides of March would have been the first full moon of the new year.

The Roman calendar changed its form several times between the founding of Rome and the fall of the Roman Empire. The common calendar we generally use today is known as the Gregorian calendar. It is a slight refinement of the Julian calendar used after by the Romans after 46 BC.

The Ides of March would have been marked with several religious observances and became  famous then and now as the date of the assassination of Julius Caesar in 44 BC. Caesar's death was a turning point in Roman history, often shown as the turn from the Roman Republic to the Roman Empire.

March (then called Martius) is the third month in the newer Julian calendar, but in the oldest Roman calendar it was the first month of the year and so it was treated as a time of new year celebrations.