The year of Caesar's fix was a mess: about 445 days long*. Some called it "the year of confusion," according to the William Smith, A Dictionary of Greek and Roman Antiquities, entry on the calendar. Macrobius (A.D. 395-423), the Roman grammarian known for describing the Roman winter holiday of Saturnalia, had a different label for 46 B.C. He called it the last year of confusion.
Caesar set up a modern-looking regular year with 365 days, plus a fix for the leap year every four years. The modern calendar is said to be 365.25 days long, so this looks equivalent, but it's not. First of all, Caesar's fix and his death so soon after reforming the calendar caused confusion because the Romans used inclusive counting, instead of the exclusive counting we use: Four years was interpreted as three. By the time of Augustus (ruled c. 31 B.C. - A.D. 14), the newly-reformed calendar already required fine tuning. Secondly, the calendar is not exactly 365.25 days. It's a few minutes shy of that, a problem the Gregorian Calendar fixed by reducing the number of leap years.
Caesar probably lined up New Year's Day with the Kalends (the 1st day) of January. The Kalends of January is roughly the time when daylight is at its shortest. New Year's Day had, earlier in Roman history, been March 1, although alongside the official religious calendar, there had been a secular calendar that started in January.
Plutarch in his biography of Numa writes:
"That the Romans, at first, comprehended the whole year within ten, and not twelve months, plainly appears by the name of the last, December, meaning the tenth month; and that Martius was the first is likewise evident, for the fifth month after it was called Quintilis, and the sixth Sextilis, and so the rest; whereas, if Januarius and Februarius had, in this account, preceded Martius, Quintilis would have been fifth in name and seventh in reckoning."
"It was also natural that Martius, dedicated to Mars, should be Romulus's first and Aprilis, named from Venus, or Aphrodite, his second month; in it they sacrifice to Venus, and the women bathe on the calends, or first day of it, with myrtle garlands on their heads."
In his Fasti 2.48-54, Ovid says that January became the start of the year under the decemviri.
"Early Roman Chronology and the Calendar," by Van L. Johnson. The Classical Journal, Vol. 64, No. 5 (Feb., 1969), pp. 203-207
A side note: The Roman calendar was divided into periods, based on the cycle of the moon, known as the Kalends, Ides, and Nones. The Kalends is thought to have originally corresponded with the new moon, and the Ides, with the full moon. Days of this calendar are counted backwards from the next Kalends, Ides, or Nones. This is not a week-based calendar. However, the published secular calendar included the letters A-G for the "Nundinae" or 8-day market weeks. See: "The Superstitions about the Nundinae," by Van L. Johnson. The American Journal of Philology, Vol. 80, No. 2. 1959, pp. 133-149.
Julian Calendar Sources
The entry from the Smith dictionary says the following are ancient sources on the Julian Calendar:
- Plutarch (Caes. c. 59),
- Dion Cassius (XLIII.26),
- Appian (De Bell. Civ. II. ad extr.),
- Ovid (Fasti, III.155),
- Suetonius (Caes. c. 40),
- Pliny (H.N. XVIII.57),
- Censorinus (c. 20),
- Macrobius (Sat. I.14),
- Ammianus Marcellinus (XXVI.1),
- Solinus (I.45).
Suetonius writes the following on the subject of Julian calendar reform:
Then turning his attention to the reorganisation of the state, he reformed the calendar, which the negligence of the pontiffs had long since so disordered, through their privilege of adding months or days at pleasure, that the harvest festivals did not come in summer nor those of the vintage in the autumn; and he adjusted the year to the sun's course by making it consist of three hundred and sixty-five days, abolishing the intercalary month, and adding one day every fourth year. Furthermore, that the correct reckoning of seasons might begin with the next Kalends of January, he inserted two other months between those of November and December; hence the year in which these arrangements were made was one of fifteen months, including the intercalary month, which belonged to that year according to the former custom.
* This number may be wrong. The most likely number other than 445 is 443, but there are other possibilities. If the topic interests you, read the primary sources above or:
- "The Pre-Caesarian Calendar: Facts and Reasonable Guesses," by H. J. Rose. The Classical Journal, Vol. 40, No. 2 (Nov., 1944), pp. 65-76.
- "Nundinae and the Chronology of the Late Roman Republic," by A. W. Lintott. The Classical Quarterly, New Series, Vol. 18, No. 1 (May, 1968), pp. 189-194
- Mommsen: History of Rome Vol. 5, p. 438
Read more in Roman Calendar Terminology.
Calendar and Time FAQ Index
- What are the Nones?
- When is Quintilis?
- What is the Julian Calendar?
- What is the significance of the number 60?
Julius Caesar FAQ Index
- Was Caesar the father of Brutus?
- Which Brutus could have been Caesar's son?
- Did Julius Caesar Say it?
- Who is the Julian Calendar named for?
- When was Quinitilis?
- When Did We Switch From the Roman Fasti Calendar to the Modern?
- What Was the Format of the Roman Fasti Calendar?
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