Let's imagine the Pope sees his Comtat Venaissin restored after the Napoleonic Wars.
The butterfly effect will grow exponentially but still, it's apparently such a meaningless move that I can't see butterflies altering the macro events in the next decades - the Spring of Nations, the rise of Napoleon III, a Savoy-led unification of Italy...
IOTL the Pope played all that Prisoner in the Vatican role because he had nowhere to go. If the Italians move in, it's been suggested that he could just retreat to Avignon and keep sovereignty there. This would definitely butterfly away any Lateran Treaty because the Pope already has his own statelet. He'd eventually accept the Italian sovereignty over Rome but I wonder if he'd ask for extraterritorial status for the Vatican Palace and occasionally or permanently set up residence there...
Another thing that should be weighed in is a little boring because it will converge with OTL. Napoleon III was a pal for his friends but he asked for something back. He accepted to recognize the expansion of the Kingdom of Sardinia at the cost of Nice and Savoy. He accepted to protect the Pope from Italian annexation to please Catholics. But ITTL how likely would it be that Napoleon III would demand Avignon in exchange for garrisoning Rome?
The butterfly effect will grow exponentially but still, it's apparently such a meaningless move that I can't see butterflies altering the macro events in the next decades - the Spring of Nations, the rise of Napoleon III, a Savoy-led unification of Italy...
IOTL the Pope played all that Prisoner in the Vatican role because he had nowhere to go. If the Italians move in, it's been suggested that he could just retreat to Avignon and keep sovereignty there. This would definitely butterfly away any Lateran Treaty because the Pope already has his own statelet. He'd eventually accept the Italian sovereignty over Rome but I wonder if he'd ask for extraterritorial status for the Vatican Palace and occasionally or permanently set up residence there...
Another thing that should be weighed in is a little boring because it will converge with OTL. Napoleon III was a pal for his friends but he asked for something back. He accepted to recognize the expansion of the Kingdom of Sardinia at the cost of Nice and Savoy. He accepted to protect the Pope from Italian annexation to please Catholics. But ITTL how likely would it be that Napoleon III would demand Avignon in exchange for garrisoning Rome?