[Enjolras pauses, making a thoughtful sort of hum as he considers that.] Not so overtly as all of that, but he speaks of a world in which the same cycle of events occurred up to the manner of our deaths.

The Great Republic had a calendar of its own, drawn up to represent the new dawn of rebirth in France. When it fell, so too, did the calendar. He uses that same measure of dating, even while addressing the fact that so much else changed. It is an assumption, but a reasonable extrapolation given what I've been told.