I think if Britain intervened in the ACW, a lot of Irish Americans would try to somehow use that fact to achieve Irish independence. We had the Fenian raids IOTL, after all.
Hard to say. Lincoln's reconstruction plan was moderate, and with the 10% plan and a protection of non-slave property, almost weaker than Johnson. But at the same time, these rebells just dragged America into a war with Great Britain (or france). That's gonna piss people off, even moderates.
Or perhaps he could give swathes of Canada and other newly acquired possessions out in a sort of homestead act specifically for african americans.
Aren't most TL's and published works this anyway?So, say the civil war in the U.S. occurs like OTL, but a foreign power, like the British and the French intervene, only for the union to still win in the end. .