I had posted this elsewhere, and I think that it deserves to be reposted. This is a comment I made last year:
As Al Smith would often say in the face of nonsense "Let's look at the record."
From David Gleeson:
"In 1860, the eleven states that would become the Confederacy contained about 85,000 Irish residents. In the three border states lived about 95,000 more Irish, giving a total of about 180,000. This total represented about 11 percent of the 1.6 million Irish living" in the United States.
Gleeson, David T.. The Green and the Gray: The Irish in the Confederate States of America (Civil War America) (p. 7). The University of North Carolina Press. Kindle Edition.
Think about the number he puts forward from the Census. In 1860, there were 1.6 million Irish in the United States. Here is the breakdown for where these Irish-born immigrants lived:
Confederate States: 5.3% of total Irish Immigrant Population
Missouri, Kentucky, Maryland: 5.9% of total Irish Immigrant Population
Northern States (including Delaware): 89% of Total Irish Immigrant Population
Think about the problem with Tucker's 40,000 Irish-born Confederate soldiers. If there were 85,000 Irish living in the Confederacy, there were no more than 45,000 males. Of these, at least a quarter would have been too young to serve. This leaves us with fewer than 35,000 adult male Irish in the Confederacy. Some would have been too old for service in the army and others were disabled. The 20,000 Irish immigrants in the Confederate army that is usually given is much more likely than Tucker's exagerrated number.
Even the 20,000 estimate may be high. The white population of the Confederacy was 5.5 million and the upper estimate of the size of the Confederate army was 1 million, or 18% of the total population. If the same ratio held for Irish in the South, the number in the army would be 15,000 to 16,000.