The Roman Calendar: From Romulus to Caesar

The way that we track the months and years can be traced back to a number of different calendars, but for many people in the world, the modern version that they know began with the Roman calendar and evolved into what they use today.

The evolution of this vital method for telling time began with the rise of the Roman Empire and it received changes and corrections multiple times before it became the one that your or I use today. Let’s explore the history and changes that resulted in the modern day calendar for many of us in the world.

The Original Calendar of Rome: An Overview

The first calendar used by Romans is widely regarded as being a lunar calendar. It is theorized that this original form was based off of the Greek lunar calendars. These calendars worked on the time between new moons, which on average is 29.5 days.

This calendar divided the months into hollow (29 days) and full (30 days) versions. The full months were considered powerful and filled with good fortune, while the hollow months were considered to be unlucky. Current calendars number the months from beginning to end, but the ancient Roman calendars counted backwards each month from three different points: the Nones, the Ides, and the Kalends.

The new month was declared when the moon’s crescent phase was first observed in the west after sunset. Depending on how far along the moon was to a new moon phase, the number of days that remained until the Nones of the next month would be established.

Understanding Roman Months and Years

As previously mentioned, Romans did not count the days in a month from beginning to end. Instead, they counted backwards from three fixed points in the month. Originally, these were decided by the moon’s phases, but after Numa’s reforms, they were set to fixed days each month.

Below is a more detailed explanation of how the months were counted:

In addition, the days of the calendar were each marked on the “fasti,” a public recording of events and religious ceremonies. The letters and their meanings are as follows:

The start of the year was originally in March and while it is not known for certain when the switch was made to January 1st, there are there. Ancient authors point to Numa Pompilius as the one who changed it. The name January for example is derived from Janus because the god was known to face both ways.

During the time of the Roman Republic, the years were counted and named based on the consuls who were elected during that term. In later years the scholars and historians started counting the years based on when Rome was founded. The exact date was not something they could agree upon though, and this resulted in varying years.

The Calendar of Romulus

The original calendar for the Roman Empire was invented by Romulus, the mythical figure who founded Rome, according to writers of the time in circa 753 BC. This original calendar had ten months and began on the spring equinox. Each month is listed below, along with a small explanation of the title.

  1. Martius (31 days)

Until roughly 153 BC this month was the first of the calendar in the Roman Empire. After this switch it became the third month after Februarius and before Aprilis. This is one of the few months named after a Roman god, in this case Mars. His sons in Roman mythology were Romulus and Remus.

This month was very heavily lined with religious observances throughout the time of the Roman Empire. It was also the time for farming, military excursions, and sailing.

  1. Aprilis (30 days)

On the first calendar of the Roman Empire this was the second month, but on later versions it was the fourth. This was a major month for farmers; therefore the month was filled with festivals celebrating various aspects of rural life.

A major celebration during this month was the founding day of Rome known as Parilia.

  1. Maius (31 days)

In later calendars, this was the fifth month, but in the first iteration it was the third. This month was marked as one of promiscuity as it heralded the festival known as “Ludi Florae” in latin which translates to “the games of Flora.” It was celebration that lasted six days and was focused on the goddess Flora.

There were theatrical performances, nude dancers, and circus events during this festival. In contrast, the middle of the month was devoted to remembering the lemures, or restless spirits of the dead.

  1. Iunius (30 days)

In later iterations of the calendar, this month was the sixth in line ad was referred to as Junius, in the Romulus calendar though it was the fourth month of ten. The origin of the original name is unknown, but in a poem about the calendar written by Ovid, three goddesses present three possible theories for the name.

They relate the world to various meanings including “youth”, “young”, and “join.”

  1. Quintilis (31 days)

The name of this month is Latin for “fifth.” This was one of the longer months in the ancient Roman calendar and originally was devoted to festivals surrounding the harvest and agriculture. In later years it became known for the games in honor of Apollo.

  1. Sextilis (30 days)

This month was moved to the eighth month in a later reform, but kept the same name. In a future reform it was changed to Augustus in honor of the first Roman emperor.

  1. September (29 days)

Roughly half of this month was devoted to the “Ludi Romani” or the “Roman Games.” These were the oldest games created by the Romans and date back to 509 BC. This was also the birth month of at least four major Roman emperors, despite it being move to the ninth month of the year in later calendars.

  1. October (31 days)

Like September, this month kept the same name throughout the original and preceding iterations of the calendar. October marked the end of military campaigns and of the farming season.

  1. November (29 days)

This month marks the ninth out of ten months in the ancient Roman calendar. Its name is derived from the Latin “novem” which means “nine.” The major event during this month was the Plebeian Games which ran from the 4th to the 17th.

  1. December (29 days)

This month’s name is derived from the Latin “decem” which means “ten.” In later reforms it was moved to the last month in the new calendar of twelve, and its length was increased to 31 days.

The Calendar of Numa

The second king of Rome was Numa Pompilius. In 713 BC he reformed the calendar in a number of ways. For starters he took one day out from each of the six months that had 30 because Romans of the time thought that odd numbers were lucky.

He took these six days and added them to 51 winter days which had never been used in the calendar. With a total of 57 days to work with, he divided them into two months: January and February. He placed these two months on the beginning of the calendar before Martius and gave the former 29 days and the latter 28.

In total, the new calendar had 355 days instead of 304 which made it a total of 12 lunar months. There were other changes though. For example, February consisted of two parts: the first part ran until the Terminalia festival on the 23rd, which was a celebration of the Roman god Terminus.

This god was responsible for protecting the borders and was originally worshipped beginning with the reign of Romulus. The last five days in February formed the second part of the month. To accommodate the solar year and ensure that alignment was maintained, a leap month was added called the “Mensis Intercalaris” on alternating calendar years.

This added month took place within February and did not interfere with the dates of festivals such as Terminalia. These leap years ended up being anywhere from 377 to 378 days long as a result. It all depended on whether the intercalary month was inserted before, or after the festival.

The added month had 27 total days which was 22 days added on to the remaining five days in February after the festival was completed. The Nones were on the fifth and the Ides were on the 13th like normal.

The role of “Pontifex Maximus” was given to the person who would decide the years where an intercalary month was added, among other things that this religious role required of them. Over the course of the Roman Empire though, this system was neglected no less than twice. During the Second Punic War it most certainly was not used.

The second time we are aware of was in the first century BC and it is assumed this neglect was a result of rising anger and chaos amongst the Roman politicians of the time. Interestingly enough, the role of Pontifex Maximus was not something a person did full-time. It was usually a role given to elite members of the Roman society.

As a result of this, corruption was hard to avoid. The person who took the role of Pontifex Maximus would have a keen eye into the politics of the time and could manipulate them accordingly. The Roman magistrates of the time were given terms that lasted a year before they were replaced. The person in charge of the calendar could easily lengthen or shorten a year depending on who was in power and if they were allied with them.

Julius Caesar was a perfect example of this. During his third consulship in 46 BC, he made the year 445 days long.

The Julian Calendar

This calendar was a major reform of the Roman calendar. It was introduced by Julius Caesar in 46 during his time as Pontifex Maximus. It took full effect the following year after the Romans conquered Egypt. For a time it was the dominant calendar across the Roman world, Europe, and in the Americas until was replaced by the Gregorian calendar in 1582.

The Julian calendar itself has a year consisting of 365 days divided into 12 months, and a leap day added to February every four years. This is a system we are quite familiar with. The concept of the calendar was to align with the tropical (or solar) year, however the tie was off by several minutes which Roman astronomers had known for some time prior to these reforms.

Since this was not something the Julian calendar accounted for, the calendar gained three days every four centuries. The Gregorian reform fixed this, but currently the Julian calendar is 13 days behind.

The Basis for Today’s Calendars

While it did go through a number of changes, the Roman calendar was the basis for what we have today. Most countries use the Gregorian calendar and the Roman Catholic calendar has also been switched to it as the basis for their liturgical calendars which decide the dates of moveable feasts like Easter.

Some Orthodox churches still use the Julian calendar, or a modified form of it, but the fact of the matter remains: we owe our modern months to the innovations of the Roman people so long ago.