They expected the Pope to take over the Western US. Lyman Beecher wrote that he went to Cincinnati from Boston "to battle the Pope for the garden spot of the world."
To give you some perspective, well more than 80% of our country lies to the west of Cincinnati, and the Vatican DID have a history of conquest way back when. So...the similarities are there.
Sorry again, it's just not something that makes sense to an aussie, it sounds like the entire US was on the edge of it's seat, yelling THE CATHOLICS ARE COMING!
What YEAR was this?