From the enslaved people, songs, chants and demands,
The princes and lords are held captive in prisons:
In the future by such headless idiots
These will be taken as divine utterances.
The French Revolution technically began when the Bastille was attacked on July 14, 1789. Members of the aristocracy were imprisoned and many lost their heads - as did the mob, metaphorically, while engaging in their violent actions.
Of course, looking at the quatrain closely, you can see that it isn't very specific. The reference to the heads is really the only thing that sticks out. Really, you can pretty much apply it to any revolution.