How was Julius Caesar responsible for the longest year in human history?

Everybody knows that the standard year has 365 days. But that is actually a fairly controversial statement historically, as well as being scientifically inaccurate. As was discussed in our article about leap days, the true time it takes for the Earth to travel around the sun is around 365.2425 days long.

However, not every calendar even follows the same way of tracking time. Lunisolar calendars, which typically track months by the phase of the moon, frequently have to add in additional months from time to time in order to line up better with the solar year.

Long story short: time is weird. Humanity has tried to create a consistent system of measuring hours and days for thousands of years, but no method has been able to completely solve the problem.

This led Julius Caesar, of Rome, to create a new system: the Julian Calendar. In large part, this calendar was the same as the one we use today. But in order to get all of the pieces to fall into place, he first had to fix all of the time slips that had happened before him. This led to the longest year in recorded history, sometimes called the annus confusionis: the Year of Confusion.

The Roman Calendar

Historians know an awful lot about the way that Ancient Rome operated, but the way that they kept time before Julius Caesar is still somewhat in doubt. There is a rough understanding of how different months were understood and where festivals and holidays fell in those months, but they were not as consistent as we might like them to be.

Ancient Romans measured time with ten months, excluding the period of winter when most agricultural work would not be done. This explains the names of four of our modern months (and two others, which were renamed at the start of the Roman Empire). These include Quinctilis (5), Sextilis (6), September (7), October (8), November (9), and December (10). Days in winter, then, were simply not counted.

The first two months were then added relatively early in the Roman Monarchy, although they still didn't line up perfectly with the solar year. There were about eleven days unaccounted for, which pretty quickly caused problems. The political and religious leaders of Rome were thus expected to add an extra month (Mercedonius) as needed to keep seasons consistent.

However, this was not done in an organized manner, which has made it difficult for historians to know precisely when certain events happened. After all, some years simply ran on longer than others. By 46 BC, the seasons were three months behind where the calendar said they should be.

What did Julius Caesar do?

The discrepancy between dates and seasons was becoming an increasingly frustrating problem. This was in part because the process of intercalation (adding days) was seen as unlucky. Nobody wanted to be the one to create an unlucky year, but clearly something had to change.

Julius Caesar sought the advice of an astronomer while he was visiting Cleopatra in Egypt, who helped him create a plan to fix the calendar by creating one very long year. Rather than the usual 355 days, 46 BC was 445 days long.

In order to make this possible, Caesar created a new calendar that would be used moving forward (with month lengths virtually the same as is used in the modern day) and added three one-off extra months to catch up properly. He also established the tradition of an extra day every fourth year.

If the same actions were to be taken today, the year would look something like this:

January, February 1-24, Mercedonius (27 days), March, April, May, June, July, August, September, October, November, Bonus month (33 days), Bonus month (34 days), December.

This solved a problem, but it also made for a very weird year for those living through it, who had to acknowledge random swathes of time that didn't existed before. It's strange enough to be a child born on a Leap Day in modern times, but what about those born in the intercalary months of 46 BC?

Thanks to the interference of Julius Caesar, the annual calendar remained relatively consistent for the next thousand years. However, his methods were also not perfect. Pope Gregory XIII ended up slightly altering the way a year is measured, which required artificially making one of history's shortest years.

But that's a story for another time. There is plenty of debate in modern times, as well as literal civil wars in his own time, about the efficacy of Julius Caesar as a leader, but it cannot be said that he was irrelevant. We need only look at the modern construction of the months, which might be best contemplated during July—the month that was posthumously named after the Roman leader himself.

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