22nd September

This day in 1792 was proposed by Jérôme Lalande as the first day of the French Revolutionary Calendar. By coincidence, it coincided with the autumn equinox.

Thus, the sun illuminated both poles simultaneously, and in succession the entire globe, on the same day that, for the first time, in all its purity, the flame of liberty, which must one day illuminate all mankind, shone on the French nation.

See THIS LINK.