Gregory's Server
Today I learned, thanks to the Wikipedia front page, that when the US was first being formed, Rhode Island took 3 years to ratify the Constitution (thus joining the US). This was due to a mix of rationales good and bad but one of the big ones was that the state had a big Quaker population who opposed slavery. They only joined the US after the US threatened a trade embargo on them, and even then they demanded the abolition of slavery. Which they didn't get. But still.
https://en.m.wikipedia.org/wiki/Ratification_of_the_United_States_Constitution_by_Rhode_Island
So basically the US used an embargo, with its explicit threat of violence attached (you can't embargo without a military to enforce it), to force abolitionist holdouts to join the United States.
(Rhode Island of course was not a monolith and there were like, antidemocracy people in the mix who didn't want to join the US for their OWN weird reasons.)