After the execution of Louis XVI and the proclamation of the First Republic, the French decided they needed a new calendar to go with their revolution. The Gregorian calendar (the one we largely use today) had too many religious elements, they determined, to be appropriate for use in their new Republic. So, they created their own. It was be the French Republican Calendar.
Pierre-Sylvain inspired this system with a secular calendar he first presented in 1788. The names of the months are inventions of a poet known as Fabre d’Égalantine, and include a mix of French words combined with Greek and Latin roots.
This new system was to be entirely unassociated with Christianity. The year began on the autumnal equinox, and all months had new names. Additionally, there would be no more Saint’s Days; instead, all 360 days of the regular calendar had their own names. They were all natural features (trees, flowers, fruits, animals, trees) or agricultural tools.
A New System
France adopted this system in 1793, on October 5 (or 1 Vendémiaire, Year II). It hadn’t been invented and implemented until that year. However, records were aligned to show that it had begun in 1792, when the First Republic was declared.
For years, this Republican Calendar was the official calendar of France. It was used to mark the chaos of the Reign of Terror, then the execution of Maximilen Robespierre (10 Thermidor Year III), and eventually, Napoléon’s ascent to Emperor (11 Frimaire, Year XIII).
After 13 years, The French Revolutionary Calendar retired, per order of Napoléon’s regime. January 1, 1806 marked the official reinstatement of the Gregorian Calendar in France.