Sadly, I have discovered, you can't believe everything that you read on the web. I wasn't blogging three weeks ago, so I missed the ideal date for this particular story, but if I wait until next year I'm bound to forget.
It is a truth universally acknowledged, that on 4 July 1776 George III wrote in his diary "nothing important happened today". A Google search on ["George III" diary nothing happened today] brings up about 17,400 hits; it says so in Wikipedia; and every year National Public Radio in the US conclude their reading of the Declaration of Independence with the same point. So it must be authentic, no?
No. It is totally untrue. But it does have a sort of basis in fact.
George III didn't keep a diary, as far as I have been able to establish. On the other hand his contemporary, Louis XVI of France, kept a Game Book. This was a journal in which he made a note of all the birds and beasts that he hunted or shot. On 14 July 1789, having shot no game, he wrote in it "rien". The Game Book can be found in the French National Archives.
So if you ignore the function of a Game Book, and if you expand on the laconic entry, you could argue that on Bastille Day, Louis XVI wrote in his diary that nothing happened.
A good story, albeit that it takes a little bit of embellishment of the truth. Too good a story to waste on a French King perhaps? So it appears that somebody embellished it further by transferring it to another King, and another day of revolution. And because so many people wanted the story to be true, it has taken wings on the web and has penetrated all kinds of places where it really out to have been checked out.