KClO3 was invented by the French in 1788.
The cowardly firework law is English, however.
They must've invented it for the Revolution they had planned for the next year, considering the storming of the Bastille happened in 1789 and Marie Antoinette was beheaded not long after.
We in Australia used to celebrate Guy Fawkes Day on Nov 5 up until the 70s, when governments banned crackers and other fireworks for public sale. The only people allowed to operate fireworks are those professionals with permits at events.