The French Republican Calendar

Messidor is the 10th month of the Republican calendar that was created
on October 6th, 1793 to honor the first French republic. The start date of
the calendar was the day the French republic was proclaimed the autumn
equinox, September 22nd, 1792. The week as we know it was replaced
by a ten-day cycle called a 'decade'. Three decades completed a month,
and at the end of the last month of the year (Fructidor), 5 days (6 days during
leap years) were added to complete 365 days. The week days were
changed to Primidi (day one), Duodi (day two), Tridi (day three), and so on.
The twelve months of the Republican calendar were named by the poet
Philippe Francois Nazaire Fabre. He used the seasons and natural events
to come up with the names as follows:

1. Vendemiaire (meaning grape harvest in Latin. The Gregorian calendar’s
   date of the first day of the first month (Vendemiaire) of the first year of the
   Republican calendar was September 22nd, 1792 and the last day of that same
   first month was October 21st 1792).
2. Brumaire (from fog in French). From October 22nd to November 21st, 1792.
3. Frimaire (from ‘frimas’ hoarfrost in French). From November 22nd to
   December 21st, 1792.
4. Nivose (snowy in Latin). From December 22nd 1992, to January 21st, 1793.
5. Pluviose (rainy in Latin). From January 22nd to February 21st, 1793.
6. Ventose (windy in Latin). From February 22nd to March 21st, 1793.
7. Germinal (bud in Latin). From March 22nd to April 21st, 1793.
8. Floreal (flower in Latin). From April 22nd to May 21st, 1793.
9. Prairial (Medow in French). From May 22nd to June 21st, 1793.
10. Messidor (‘messis’ corn harvest in Latin, and ‘doron’ gift in Greek). From
    June 22nd to July 21st, 1793.
11. Thermidor (‘thermon doron’ gift of heat in Greek). From July 22nd to
    August 21st, 1793.
12. Fructidor (‘fructus’ fruit in Latin and ‘doron’ gift in Greek). From August 22nd
    to September 21st, 1793.

On September 9th, 1805 (the 22nd of Fructidor during the thirteenth year of the Republic)
Napoleon Bonaparte I, by imperial decree, abolished the Republican calendar.
On the 1st of January, 1806, France returned to the Gregorian calendar after 13 years
of using the Republican calendar.