https://www.infoplease.com/august-history-months-origin

August—History of the Month's Origin

Updated February 28, 2017

A history of the month's name

by Borgna Brunner

Caesar Augustus

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'July' is for Julius

The Roman Senate named the month of July after Julius Caesar to honor him for reforming their calendar, which had degenerated into a chaotic embarrassment. Bad calculations caused the months to drift wildly across the seasons—January, for example, had begun to fall in the autumn.

The high priest in charge of the calendar, the pontifex maximus, had become so corrupt that he sometimes lengthened the year to keep certain officials in office or abbreviated it to shorten an enemy's tenure.

Effective January 1, 45 B.C.

The new calendar went into effect on the first day of January 709 A.U.C. (ab urbe condita—"from the founding of the city [Rome]")—January 1, 45 B.C.—and put an end to the arbitrary and inaccurate nature of the early Roman system. The Julian calendar became the predominant calendar throughout Europe for the next 1600 years until Pope Gregory made further reforms in 1582.

Certain countries and institutions in fact adhered to this ancient system until well into the twentieth century: the Julian calendar was used in Russia until 1917 and in China until 1949, and to this day the Eastern Orthodox church adheres to Caesar's calendar.

The month Julius replaced Quintilis (quintus = five)—the fifth month in the early Roman calendar, which began with March before the Julian calendar instituted January as the start of the year. Unfortunately, Caesar himself was only able to enjoy one July during his life—the very first July, in 45 B.C. The following year he was murdered on the Ides of March.

Augustus for 'August'

After Julius's grandnephew Augustus defeated Marc Antony and Cleopatra, and became emperor of Rome, the Roman Senate decided that he too should have a month named after him. The month Sextillus (sex = six) was chosen for Augustus, and the senate justified its actions in the following resolution:

Whereas the Emperor Augustus Caesar, in the month of Sextillis . . . thrice entered the city in triumph . . . and in the same month Egypt was brought under the authority of the Roman people, and in the same month an end was put to the civil wars; and whereas for these reasons the said month is, and has been, most fortunate to this empire, it is hereby decreed by the senate that the said month shall be called Augustus.

Not only did the Senate name a month after Augustus, but it decided that since Julius's month, July, had 31 days, Augustus's month should equal it: under the Julian calendar, the months alternated evenly between 30 and 31 days (with the exception of February), which made August 30 days long. So, instead of August having a mere 30 days, it was lengthened to 31, preventing anyone from claiming that Emperor Augustus was saddled with an inferior month.

To accommodate this change two other calendrical adjustments were necessary:

The extra day needed to inflate the importance of August was taken from February, which originally had 29 days (30 in a leap year), and was now reduced to 28 days (29 in a leap year).

Since the months evenly alternated between 30 and 31 days, adding the extra day to August meant that July, August, and September would all have 31 days. So to avoid three long months in a row, the lengths of the last four months were switched around, giving us 30 days in September, April, June, and November.

Among Roman rulers, only Julius and Augustus permanently had months named after them—though this wasn't for lack of trying on the part of later emperors. For a time, May was changed to Claudius and the infamous Nero instituted Neronius for April. But these changes were ephemeral, and only Julius and Augustus have had two-millenia-worth of staying power.

For further reading:

Calendar: Humanity's Epic Struggle to Determine a True and Accurate Year, David Ewing Duncan (New York: Avon, 1998).

https://www.infoplease.com/history/ancient/the-ides-of-march

The Ides of March

Updated February 28, 2017

Just one of a dozen Ides that occur every month of the year

by Borgna Brunner

Julius Caesar

As far as Caesar knew, the Ides were just another day.

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The soothsayer's warning to Julius Caesar, "Beware the Ides of March," has forever imbued that date with a sense of foreboding. But in Roman times the expression "Ides of March" did not necessarily evoke a dark mood—it was simply the standard way of saying "March 15." Surely such a fanciful expression must signify something more than merely another day of the year? Not so. Even in Shakespeare's time, sixteen centuries later, audiences attending his play Julius Caesar wouldn't have blinked twice upon hearing the date called the Ides.

The term Ides comes from the earliest Roman calendar, which is said to have been devised by Romulus, the mythical founder of Rome. Whether it was Romulus or not, the inventor of this calendar had a penchant for complexity. The Roman calendar organized its months around three days, each of which served as a reference point for counting the other days:

Kalends (1st day of the month)

Nones (the 7th day in March, May, July, and October; the 5th in the other months)

Ides (the 15th day in March, May, July, and October; the 13th in the other months)

The remaining, unnamed days of the month were identified by counting backwards from the Kalends, Nones, or the Ides. For example, March 3 would be V Nones—5 days before the Nones (the Roman method of counting days was inclusive; in other words, the Nones would be counted as one of the 5 days).

Days in March

March 1: Kalends;
March 2: VI Nones;
March 3: V Nones;
March 4: IV Nones;
March 5: III Nones;
March 6: Pridie Nones (Latin for "on the day before");
March 7: Nones;
March 15: Ides 

Used in the first Roman calendar as well as in the Julian calendar (established by Julius Caesar in 45 B.C.E.) the confusing system of Kalends, Nones, and Ides continued to be used to varying degrees throughout the Middle Ages and into the Renaissance.

So, the Ides of March is just one of a dozen Ides that occur every month of the year. Kalends, the word from which calendar is derived, is another exotic-sounding term with a mundane meaning. Kalendrium means account book in Latin: Kalend, the first of the month, was in Roman times as it is now, the date on which bills are due.

END

The 15th of March is today where I am. The Ides of March is the 15th March.