Merriam Webster:
Definition of ides
: the 15th day of March, May, July, or October or the 13th day of any other month in the ancient Roman calendar
Britannica:
You have probably heard of the Ides of March, however, because it is the day Roman statesman Julius Caesar was assassinated. The immortal words “Beware the Ides of March” are uttered in William Shakespeare’s Julius Caesar to the leader by a fortune-teller. Other bad things have happened on March 15, of course, but there’s probably no reason to beware March’s Ides more than the Ides of any other month.
In a 31-day month such as March, the Kalends was day 1, with days 2–6 being counted as simply “before the Nones.” The Nones fell on day 7, with days 8–14 “before the Ides” and the 15th as the Ides.
Oxford dictionary:
In the ancient Roman calendar, the ides is notionally the day of the full moon, and falls roughly in the middle of the month: the 15th of March, May, July, and October, and the 13th of other months. While the word can be traced to the Latin idus, the origin is unknown.
Movies are not accurate. Of those "next thirty days" only the 15th was the ides.
Nothing to do with March 4.
Definition of ides
: the 15th day of March, May, July, or October or the 13th day of any other month in the ancient Roman calendar
Britannica:
You have probably heard of the Ides of March, however, because it is the day Roman statesman Julius Caesar was assassinated. The immortal words “Beware the Ides of March” are uttered in William Shakespeare’s Julius Caesar to the leader by a fortune-teller. Other bad things have happened on March 15, of course, but there’s probably no reason to beware March’s Ides more than the Ides of any other month.
In a 31-day month such as March, the Kalends was day 1, with days 2–6 being counted as simply “before the Nones.” The Nones fell on day 7, with days 8–14 “before the Ides” and the 15th as the Ides.
Oxford dictionary:
In the ancient Roman calendar, the ides is notionally the day of the full moon, and falls roughly in the middle of the month: the 15th of March, May, July, and October, and the 13th of other months. While the word can be traced to the Latin idus, the origin is unknown.
Movies are not accurate. Of those "next thirty days" only the 15th was the ides.
Nothing to do with March 4.