Trying to find info on the development of railways in the 1800s, specifically railroads between countries, to the extent that such things existed at all. Basically if you've got two countries that historically have not like each other, but they're currently at peace, how much of a liability would it be for a railway between them? Would it be a big enough deal that neither would allow a railway to be built to the edge of their borders, or would it be not much of a big deal? Trying to wrap my head around the logistics of the situation.
Different gauge rails actually makes a lot of sense. So no matter what your trains can't reasonably go into their territory. Might go for that as a simple solution.
Some countries also had a bunch of different rail gauges internally as well just due to uncoordinated construction, like IIRC both Austro-Hungary and Russia suffered from this as late as WWI.
I found this: https://en.m.wikipedia.org/wiki/Break_of_gauge
However it doesn't really talk about this being used to prevent trains from running into hostile territory. Maybe it's implied