I wanna say America, but I think it was more complicated.
I believe it was the Scots, originally. Throughout the 18th Century, key Scottish leaders were urging London to grant independence, but the English kings and queens kept giving them some lame excuse about Scotland being on the same landmass and independence not working that way. To which the Scots replied "WELL EXPLAIN IRELAND THEN!" but the English were busy going for a Domination win and couldn't be bothered by a few unhappy citizens. The Scots knew if they were ever going to be their own country, they would need some sort of tech advantage, and they knew the French were going all-out for the Lib race. They managed to get there first with Hume, but they weren't sure what to do with Lib now that they had it. James Watt suggested they get Steam Power, so they did, and discovered that Great Britain had, like, ALL THE COAL, which England quickly used to spam Redcoats and began conquering even faster. Scotland realized that a large amount of "England's" coal was actually in Scotland, but with the Scottish UU being "crazy blueface man with big sword" and rather obsolete, they knew they had no chance of ever defeating England.
The Scottish leaders stewed on this one for a while- they had beaten the French to Liberalism in an effort to win their freedom, only to help the English in the long run. So since London seemd rather uninterested in religious tolerance, most of the Scots set sail for Virginia to join that weird new country whose Unique Ability was "pick at the British army until they get irritated and leave". (The Scots had used this tactic with limited success for centuries, but they figured with an ocean between them and England they'd have a better chance.) They offered Liberalism and Steam Power to Washington- just to trade away the English tech lead, like a good vassal- and the Americans decided that since we were
severely behind in both culture and technology, we'd jump into Free Speech and Free Religion.
This has been your "when TMM wanders through Wikipedia" alternate history lesson.
