What is the Ides of March? Here's why it demands caution.

As the calendar turns to March, many people have likely heard the phrase "beware the Ides of March." Some may be asking exactly what the Ides of March are.

The phrase is widely known from William Shakespeare's "Julius Caesar," when a soothsayer warned Caesar to "beware the Ides of March." Caesar was later assassinated by Roman senators on March 15, 44 B.C.E.

The history behind the Ides of March actually has a much less sinister origin.

Why is it called the Ides of March?

According to the History Channel, Kalends, Nones and Ides were ancient markers used to reference dates in relation to lunar phases.

"Ides simply referred to the first full moon on a given month, which usually fell between the 13th and 15th," according to the History Channel's website. "In fact, the Ides of March once signified the new year, which meant celebrations and rejoicing."

According to Encyclopedia Britannica, the Romans divided months into groupings of days counted before certain named days. The Kalends was the beginning of the month, the Ides was the middle and the Nones was in between them.

"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," according to Encyclopedia Britannica's website. The days after the Ides were counted as "before the Kalends" of the next month.

What day is the Ides of March 2024?

In 2024, the Ides of March falls on Friday, March 15.

What other notable events have happened on the Ides of March?

Since Caesar's assassination in 44 B.C.E., other ominous events have occurred on the Ides of March.

In 1939, Adolf Hitler moved Nazi troops into Czechoslovakia, annexing the country and ending the practice of appeasement. Britain would declare war on Germany in September, sparking World War II.

In March 2003, the World Health Organization declared SARS a "worldwide health threat." The disease would infect more than 8,000 people, killing nearly 800, in more than 37 countries over the course of the outbreak.