I mentioned yesterday that I was reading Roll Jordan Roll. I'm enjoying its primary source citations a bit more than its arguments. That could just be my personal bias toward story-telling. At any rate, here is a citation from Fanny Kemble, who journaled her time on her husband's Georgia plantation. She's discussing the reasons why the Irish immigrant laborers must be kept separate from the black slaves:
Now you must not suppose that these same Irish free labourers and negro slaves will be permitted to work together at this Brunswick Canal. They say that this would be utterly impossible; for why?--there would be tumults, and risings, and broken heads, and bloody bones, and all the natural results of Irish intercommunion with their fellow creatures, no doubt--perhaps even a little more riot and violence than merely comports with their usual habits of Milesian good fellowship; for, say the masters, the Irish hate the negroes more even than the Americans do, and there would be no bound to their murderous animosity if they were brought in contact with them on the same portion of the works of the Brunswick Canal.Doubtless there is some truth in this--the Irish labourers who might come hither, would be apt enough, according to a universal moral law, to visit upon others the injuries they had received from others. They have been oppressed enough themselves, to be oppressive whenever they have a chance; and the despised and degraded condition of the blacks, presenting to them a very ugly resemblance of their own home, circumstances naturally excite in them the exercise of the disgust and contempt of which they themselves are very habitually the objects; and that such circular distribution of wrongs may not only be pleasant, but have something like the air of retributive right to very ignorant folks, is not much to be wondered at. Certain is the fact, however, that the worst of all tyrants is the one who has been a slave......but the Irish are not only quarrelers, and rioters, and fighters, and drinkers, and despisers of niggers--they are a passionate, impulsive, warm-hearted, generous people, much given to powerful indignations, which break out suddenly when they are not compelled to smoulder sullenly--pestilent sympathisers too, and with a sufficient dose of American atmospheric air in their lungs, properly mixed with a right proportion of ardent spirits, there is no saying but what they might actually take to sympathy with the slaves, and I leave you to judge of the possible consequences. You perceive, I am sure, that they can by no means be allowed to work together on the Brunswick Canal.
The Iberians are believed to have been originally an African race, who thousands of years ago spread themselves through Spain over Western Europe. Their remains are found in the barrows, or burying places, in sundry parts of these countries. The skulls are of low prognathous type. They came to Ireland and mixed with the natives of the South and West, who themselves are supposed to have been of low type and descendants of savages of the Stone Age, who, in consequence of isolation from the rest of the world, had never been out-competed in the healthy struggle of life, and thus made way, according to the laws of nature, for superior races.