The Great Replacement subscribers remind me of the Know Nothings, a third-party that gained strength in the decade before the Civil War. Like the Great Replacement theorists, the Know Nothings worried about demographic change, specifically the idea that the Catholic Church was conspiring to import millions of Irish and German Catholic voters to deprive the Protestants of their God-given civil rights. Sound familiar?

If you're wondering how successful they were electorally, they ran a former President, Millard Fillmore, in the 1856 election. The movement also attracted the most famous assassin in American history - John Wilkes Booth.

Lincoln himself commented on the movement in a letter to a close friend:

"I am not a Know-Nothing. That is certain. How could I be? How can any one who abhors the oppression of negroes, be in favor of degrading classes of white people? Our progress in degeneracy appears to me to be pretty rapid. As a nation, we begin by declaring that "all men are created equal." We now practically read it "all men are created equal, except negroes." When the Know-Nothings get control, it will read "all men are created equal, except negroes, and foreigners, and catholics." When it comes to this I should prefer emigrating to some country where they make no pretence of loving liberty-to Russia, for instance, where despotism can be taken pure, and without the base alloy of hypocracy."

The more things change, the more they stay the same. The Know Nothings had a brief burst of energy, drowned out by the Civil War, but the legacy of their ideas obviously continues to live on.