First off, thanks to Thande for coming up with most of the idea for this (down to the TL name) and, of course, to Stirling for coming up with the idea of "Europeans flee meteor storm" in
Peshawar Lancers. Buy it, people!
Now, here's the basic outline:
On the 4th of July, 1749, Central Europe was devastated by a comet storm. The majority fell around the central regions of the Holy Roman Empire, but with comets landing as west as the Rhine, as east as Warsaw, as south as Milan and as north as Dogger Bank. The Dogger Bank collision was by far the largest of the storm, and the impact seeded a gigantic tidal wave that literally overwhelmed the North Sea coastlines, devastating London and subsuming almost all of the Netherlands. The Channel was not swamped to the extent seen in the northeast, but enough damage was done to render the Channel Islands uninhabitable for some years.
Here's a map showing the rough positioning of the comets (note Berlin).
For the purposes of this scenario, George II is in London and Prince Frederick is not.
Your thoughts?