French republican calendar

The French republican calendar was instituted by the National Convention after the French Revolution as a reform of the Gregorian calendar that would help to divorce the new republic from its Catholic predecessor.

The creation of the calendar

In 1793, the National Convention's Committee of Public Instruction created a subcommitte, chaired by the mathematician Charles Gilbert Romme, to create a new calendar. Other members were Louis Lagrange and Gaspard Monge, also mathematicians; the scientists Antoine François Fourcroy, Guyton de Morveau, Joseph Jérôme le François de Lelande, and Joseph Lakanal; and the poets Marie-Joseph de Chénier and Philip François Nazaire Fabre d'Églantine.

Romme presented the results, first to the Committee of Public Instruction and then to the full Convention, in September of 1793, and the Convention issued a decree on October 5th that made the calendar official. The names of days and months were finalized by a decree on November 24th.

Its structure

Start of the year

Year I was deemed to have on September 22, 1792 Gregorian, the date of the founding of the Republic, and also the fall equinox of that year. Each following year was to start at midnight of the day of the fall equinox, as observed at the Paris Observatory.

Months and days

A normal year was divided into 12 months of 30 days each, with five epagomenal days to bring it to 365 days. Each month consisted of three décades, or 10-day weeks, with days named Primdi, Duodi, Tridi, Quartidi, Quintidi, Sextidi, Septidi, Octidi, Nonidi, and Decadi ("First Day", "Second Day", etc.). Every Decadi was to be a rest day. Fabre d'Églantine named the days and months as follows:

Fall months
Vendemaire	Vintage	Brumaire	Foggy

Leap years

Leap years, called "sextile years" because of the six epagomenal days, were to occur every four years, with the first being year III. A group of four years was to be known as a Franciade. However, as was quickly pointed out by the astronomer Jean Baptiste Joseph Delambre, there was no way to reconcile this with the desire to begin every new year on the equinox. In response, Romme formed a new subcommittee to "perfect" the calendar. It ultimately proposed to follow the Gregorian pattern of leap years, with the exception of suppressing one leap day every 4000 years. Before the recommendation could be implemented, however, Romme was arrested and sentenced to death.

Its demise

The republican calendar was deeply unpopular both inside and outside France and its conquered territories for the difficulties it caused in communicating and doing business with the rest of Europe. The working people of France were also unhappy about having only one day of rest in every ten.

The décade was the first part of the calendar to go, in 1795. Also in that year, the sanculotides were renamed simply jours supplémentaires ("extra days").

Napoleon exempted Rome from the new calendar in 1799, to placate the Pope. In 1805, now emperor, he restored France to Catholicism and restored the old calendar. France officially rejoined the Gregorian world on January 1st, 1806.