Quite true. However, the societies they were rebelling against were not the liberal (in the original sense) Whig society of significant freedom the American colonists were attempting to conserve. The 48ers fought against the true Right Wing, the King and Church absolutism that the Whigs in England had triumphed against in the Glorious Revolution.
The men of 48 weren't fighting to keep their rights, because they had no rights. The 48er revolutionists were largely, though not exclusively, fighting to acquire the rights the American revolutionists were fighting to retain. But the American Revolution could be conservative only because a previous revolution, that of 1688, had acquired those rights. IOW, the conservative European societies the men of 48 rebelled against deserved to be overthrown.
Some conservatives seem to be under the mistaken impression that conservatism is always a good thing. This is nonsense on stilts. It depends utterly and entirely on what is being conserved. The conservation of evil and oppression is never a good thing.
Islamists really are fighting to conserve what they see as true Islam. Does that make their cause just? Of course not.
American conservatism is, from a long-term historical perspective, the most radical ideology in history. All other ideologies dispute over which group will be given the power to domineer over others. Only the true American ideology American conservatism attempts to conserve tries to keep any group from domineering, allowing the people to lead their own lives as they see fit.
This has never been fully or perfectly implemented, of course, and is in the process of slipping away, but it is what the American project stands for.
I agree with you that it’s a mistake to conflate Continental European conservatism with that of America or even its parent England.
But I don’t think that affects my point that 1776 was an independence movement, whereas 1848 was both a social and political revolution.
1776 was a revolution that replaced monarchy with self government. It was a political revolution, but it left daily life intact. There was no “class struggle”.
1848 was another matter. It was an attempt to overthrow the old order, socially as well as politically. The 48ers encompassed a wide variety of beliefs, from Whigs all the way to the likes of Marx and Engels.
Just as it’s a mistake to equate Continental conservatism with that of America, it’s a mistake to equate the 1848 revolutionaries with those that led to the creation of the American culture.
“American conservatism is, from a long-term historical perspective, the most radical ideology in history. “
I don’t know that I’d agree with you here; like Russell Kirk I believe that American conservatism is the absence of ideology; when what you have is an ideology it’s something other than conservatism.