The one thing it’s hard to imagine anyone stopping was the smallpox and such. It would have happened sooner or later unless the entire progress of technology was put on halt. Mass deployable vaccines before transoceanic sail ships seem unlikely. Someone would have gotten to the other side and even had their intentions been the best possible, people would have died out of sheer ignorance.
I don’t know if you need vaccines. From memory, the incubation time of smallpox is about half the transatlantic voyage time (2 weeks versus 4 weeks)? I don’t know how much we know about how the first smallpox case crossed the Atlantic, or whether it happened more than once. But I wonder whether a policy on long voyages of “if we notice someone on board has smallpox, we make them walk the plank to protect everyone else on board” (not even thinking about the people at the destination) might have been a) possible in a nearby world and b) effective?
(I’m vaguely aware that the voyage wasn’t nonstop, they’d go via e.g. the Azores(?), presumably with a chance to pick up smallpox there. Maybe that sinks the idea.)
I don’t know if you need vaccines. From memory, the incubation time of smallpox is about half the transatlantic voyage time (2 weeks versus 4 weeks)? I don’t know how much we know about how the first smallpox case crossed the Atlantic, or whether it happened more than once. But I wonder whether a policy on long voyages of “if we notice someone on board has smallpox, we make them walk the plank to protect everyone else on board” (not even thinking about the people at the destination) might have been a) possible in a nearby world and b) effective?
(I’m vaguely aware that the voyage wasn’t nonstop, they’d go via e.g. the Azores(?), presumably with a chance to pick up smallpox there. Maybe that sinks the idea.)