First things on twitter it is a scandal for any catholic to support ethno nationalism—it violates church teaching and betrays our history. hkxdxex4vu   2016 07 30 12.06.08
Ethno-Nationalism In The News: The MSM Doesn't Like It
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July 30, 2016, 08:29 AM
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Found in the New York Times, by Presidential historian Gene Healy:

Yes, if Colonel Roosevelt wasn't a "blood and soil" nationalist, there isn't  such a thing. As Peter Brimelow wrote in National Review, back when it was more National that it is now

John Jay in The Federalist Papers wrote that Americans were “one united people, a people descended from the same ancestors, speaking the same language, professing the same religion, attached to the same principles of government, very similar in their manners and customs.” Some hundred years later, Theodore Roosevelt in his Winning of the West  traced the “perfectly continuous history” of the Anglo-Saxons from King Alfred to George Washington. He presented the settling of the lands beyond the Alleghenies as “the crowning and greatest achievement” of “the spread of the English-speaking peoples,” which—though personally a liberal on racial matters—he saw in explicit terms: “it is of incalculable importance that America, Australia, and Siberia should pass out of the hands of their red, black, and yellow aboriginal owners, and become the heritage of the dominant world races.” [Time To Rethink Immigration, 1992]
Here's another take on nationalism, from the mostly Catholic magazine First Things:

The cartoon you see isn't so much about Catholic history in general as it is about Protestant American resistance to Catholic immigration, and the concomitant political influence of Roman Catholic bishops. But modern European nationalism has nothing to do with the Catholic vs. Protestant wars, but is caused by resistance to Muslim immigration from outside of Christendom—a word you don't hear much.

I saw this anti-nationalist First Things tweet because it was retweeted by AsianConservativeMan who wrote: "And the Pope's demand for a flood of murderous rapists into Europe totally accords with Church teaching and history."

In fact, a previous flood of murderous rapists (I. e. Muslims) was what caused a ninth-century Pope to build the still extant wall around Vatican City.