Bastille Day]. It marks the beginning of the French Revolution.
One of Ms. Sandwalk's ancestors is William Playfair, inventor of pie charts and histograms [Bar Graphs, Pie Charts, and Darwin]. He's famous because he knew Erasmus Darwin. He's also famous because there are stories that he took part in the Storming of the Bastille while living in Paris.
One the other hand, there are plenty of things for which he is less than famous [William Playfair] and there's a a good reason why his children left England and migrated to Canada becoming farmers near Perth, Ontario.