The French Revolutionary Calendar was created and implemented during the French Revolution. It was used by the French government from late 1793 to 1805. There is an excellent table by Dieter Echterhoff (please see the attached pdf-document*) to convert these dates to the Gregorian calendar.
Example: "25 ventrose an 11" = March 16th, 1803
* The use of the pdf-document "Der Französische Revolutionskalender" is with kind permission of Dieter Echterhoff ( http:/www.lzkv.de )
