The French Revolutionary Calendar

At a certain point, the dominant revolutionary party in France decided that the new Republic needed to be purged of all traditional, Christian and monarchical symbolism. The new calendar went far beyond a mere renaming of the months. The year and the months were given new starting points, and new names based on the seasons, the weather and the agricultural year were devised.

French historians of the Revolution often use the new calendar when discussing the events of the most turbulent period of the Revolution, in part because that is how dates are identified in the documents they study, but also (I think) because using them gives modern people a feeling for how the Revolution seemed to all concerned as a whole new era of the world. If you are not steeped in this stuff, however, you may find it rather difficult to figure out when the Year II was, or the month of Thermidor.

But wait! Brittanica has an attractively illustrated primer on the months of the Calendar. I think lots of people may find this useful.

Image: One of the great Revolutionary celebrations: the Festival of the Supreme Being 20, Prairial Year II (8 June 1794).