The Ides of March fall on the 15th calendar day of March, although the date has also become intimately associated with the assassination of Julius Caesar, who was murdered in the Roman Senate on 15 March, 44 BC. Because the death of Caesar marked a radical change in Roman society, the time is familiar to most scholars of Western history, along with fans of Shakespeare, who remember the line “Beware the Ides of March,” from his play Julius Caesar. In modern days, the date carries a sense of menace and doom, because of this association.
However, originally, the Ides of March carried no special meaning; it was merely part of the Roman calendar. The days of each month used to be counted in relationship to Kalends, the first day of the month, Nones, the seventh day, and Ides, which fell in the middle of the month — somewhere between the 13th and the 15th, depending on the month. Usually, Ides fell during the full moon, and it was actually an auspicious day in Roman society. This may explain why Caesar did not heed the warning of an anonymous soothsayer. The terms Kalends, Ides, and Nones were used in various parts of Europe through the Renaissance before being abandoned, and Shakespeare's original audience probably would not have found his phrase at all remarkable.
According to contemporary historical accounts, Julius Caesar was warned several times that he should “beware the Ides of March” by a soothsayer who prophesied that Caesar was in danger on that date. Given the complex plot surrounding Caesar's assassination, it is possible that the soothsayer had good reason for picking the time period. By staying home, Caesar could have avoided his fate in the Senate, but he chose to go anyway, and legend has it that he encountered the soothsayer for the last time just outside the Senate, with the soothsayer reiterating his warning.
While the Ides of March has taken on sinister implications in modern society, Caesar probably viewed it as another ordinary day until he was stabbed 23 times and left to bleed to death in public. Caesar was at least clearly aware of a growing civil unrest, and certainly pushed at the boundaries of Roman society and tradition. Had he used caution, he probably would have survived that assassination, but it is likely that he was already doomed by his political decisions.