The Potato Famine vs. Hurricane Katrina

While I wrote the book, I thought of this. Moriarty thinks the British were happy to drive the Irish out and the evidence is sort of there.
Why sort of?

With both the Potato Famine and Hurricane Katrina, I don't think the powers that be "planned" the depopulation. With both situations, the powers that be may have been happy that the respective places were depopulated.

In the Potato Famine, Irish farming could be made more "productive." In New Orleans, the population changed.

Not sure myself what is true. I am just throwing it out there.