The Ides of March is the 15th day of the month and, in ancient Rome, it was the standard way of saying the date. The ancient Romans would use Kalends for the first day of any month, Nones for the 7th day in March, May, July, and October, but the 5th day in other months, and Ides for the 15th day in March, May, July, and October, but the 13th day in other months. For identifying the other days of the month they would count backwards from the Kalends, Nones, and Ides. For example, March 2nd would be VI Nones. Also, the Ides of March was the date of Caesar's death in 44 B.C.
"Beware the Ides of March," a soothsayer says to Caesar. Caesar responds, "He is a dreamer; let us leave him: pass." These are famous lines from the play "Julius Caesar" by William Shakespeare. "Beware of the Ides of March" refers to the day of Caesar's death, but Caesar does not think any thing of it, and he just says to his soldiers to pay no attention to him, and to pass by the soothsayer.
It is believed that the unidentified person in Shakespeare's play was actually Spurinna, a Roman astrologer. Caesar actually did pay attention to the warning by Spurinna because he was going to stay in his bedroom chambers on March 15th so he would be safe. However, Decimus Brutus convinced Caesar to come out on that day, because he said that the astrologer's warnings were just superstition.
Caesar went out on the Ides of March to go to the Senate meeting in the Temple of Venus. On his way, he ran into Spurinna, and Caesar told him, "The Ides of March have come." The astrologer then replied, "Yes, the Ides are come, but they are not past." Caesar paid no attention to Spurinna's reply and he continued to head to the Senate meeting. Later that day, Caesar was assassinated by his enemies, in the Pompey Theater, at the foot of the Pompey statue.
There is a theory on why Caesar went out on the Ides of March to go to the Senate. Since the Ides change from the thirteenth to the fifteenth on different months, Caesar may have become confused because the Ides originally stood for the date of the full moon, but since the solar and lunar calendar months were not the same, the Ides were not always the date of the full moon. Julius Caesar could have stayed around his Palace on the 13th day of March, but he had his guard down on the real Ides of March. That is why Caesar would have said to Spurinna, "The Ides have come." In conclusion, the Ides of March are March 15th on the ancient Roman calendar, and it was the day Caesar was killed. If Julius Caesar would have payed more attention to the warnings of Spurinna, he may have lived a lot longer then he did. However, Caesar still may have been killed by his enemies.