It is a joke but he can't help it. Conquest isn't just bullets and bombs. Conquest is cultural too. That's why the descendants of slaves in the US are mostly christian and why people in Dublin speak English.
The murder and genocide of the numerous American Indian nations was a tragedy, but the destruction of their cultures is a different kind of tragedy. Americanization/Europeanisation/Gentrification etc is a kind of conquest in itself.
Gramsci called this concept 'cultural hegemony':
"Hegemony' in this case means the success of the dominant classes in presenting their definition of reality, their view of the world, in such a way that it is accepted by other classes as 'common sense". The general 'consensus' is that it is the only sensible way of seeing the world.
The American government actively killed Native Americans for one hundred years and more. I think what the U.S. government did the Native Americans is just as bad, and worse than what happened to Jews in Nazi Germany. And I think it's all awful and evil. But it was all for capitalism and the state so we can "move on" so its fine, made a lot of money from buying their cheap land by expelling them and then speculating on the land. Railroads had to be built by small groups of rich white men.
America was built by immigrants from all over the world, Blacks, Women, Native Americans, Chinese you name it but only a select few profited of it. The American Nightmare.
