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Irish immigrants in the Civil War

I was cc-ed on a series of emails on a topic I know nothing about, maybe because I’m on the political science faculty here, I don’t know. Anyway, there was some statistical content here so I thought I’d share with you.

The email is from James McManus:

Analysis of the Civil War Immigrant problem

McPherson’s Immigrant Hypotheses

“Immigrants were proportionally under-represented in the Union’s armed services…Despite the fighting reputation of the Irish Brigade, the Irish were the most under-represented group in proportion to population, followed by German Catholics.”
– James M. McPherson, Battle Cry of Freedom, p 606, 1988

“The under-representation of Catholic immigrants can be explained in part by Democratic allegiance of these groups and their opposition to Republican war aims, especially emancipation…Although this group furnished a large number of substitutes and bounty men during the final year of the war — thereby achieving an inglorious visibility — they also furnished a large number of deserters and bounty jumpers.”
– James M. McPherson, Battle Cry of Freedom, p. 607, 1988

“The biases in the sample toward native-born soldiers from the middle and upper classes who enlisted early in the war are unavoidable…I am less interested in the motives of skulkers who did their best to avoid combat. My samples are skewed toward those who did the real fighting.”
– James M. McPherson, For Cause & Comrades, p. ix, 1997

McPherson’s Missing Data Problem:

“The materials available for forming a trustworthy estimate of the nativities, and even the nationality of our soldiers have been very meager…It was not until the war had been waged for some time that the State or country of birth was systematically required upon the enlistment-rolls. “
– Investigations in the Military and Anthropological Statistics of American Soldiers(Sanitary Commission Report), p. 15, 1869.

The Union army didn’t record country of birth for about 42.9 percent of the soldiers, according to Professors McPherson’s primary source the Sanitary Commission Report of 1869, aka Investigations in the Military and Anthropological Statistics of American Soldiers. Perhaps, the good professor didn’t read the nativity chapter commentary and its strong admonition about the accuracy of the report’s nativity estimates. Moreover, as noted in the commentary, the report only estimates the number of soldiers in the Volunteer units and their nativities (144,221 Irish). It did not report data or estimates for the Regular army, the Navy and Marines, the militias, and any troops enrolled for service by some western states and territories (92,000). Religion wasn’t recorded for any of the soldiers or sailors.

Medal of Honor “Sample” and Nativity Data
The 1500+ Medals of Honor awarded during the Civil War provide a good picture of the soldiers’ and sailors’ nativities (country of birth). 32 states and 20 immigrant countries are represented, including India, Malta, Russia, Spain, and Italy and even an African-America, born in Mexico, serving in a “white” regiment.

The medals indicate a large immigrant presence in the Union army (and navy) throughout the war with the Irish at 9 percent. That gives an Irish presence in the Union army and navy at about 200,000 not including another 6 or 7 percent of soldiers with a likely Irish heritage who were credited to the US, Canada, England and Scotland. The relative proportions for the Native born and Irish before and after 1863 are the same.

The Regular army and Navy had higher immigrant participation than the states “Volunteer” army.

The biases in the Medal of Honor sample are:
– Officers are over-represented
– The Medal of Honor was awarded at a much higher rate by the Navy
– Medals of Honor were awarded at a lower rate to African Americans
– There is some clustering of Medals of Honor in a few “volunteer” units. In the 8 with 10 or more awards, the Irish were outnumbered 76 to 1.
– Columbia’s Anchor Baby. Alfred Thayer Mahan’s father, leader of the faculty at West Point, like Phil Sheridan, was probably born in Ireland. Some of our “native born” soldiers may have become birthright citizens by being baptized in a Catholic Church immediately after their family’s arrival in the US.

My analysis takes these factors into account, but makes no adjustment of the “volunteer” units or anchor babies, if anything that would slightly increase the proportion of Irish-born.

Corroborating Evidence
Medal of Honor awards highly correlate with KIA and enlistments by state.

The proportions for New York State (NYC vs not-NYC) are the same (57/43 percent) for Medals of Honor, enlistments, units and KIA.

The Medal of Honor proportions suggest that 60 percent of NYC enlisted soldiers were immigrants. Units organized at New York City and Brooklyn contributed about 150,000 soldiers and 50,000 sailors and militia to the Union war effort. There is significant anecdotal evidence to that effect.

Age Cohort Survival Model (ACS)
Since the 1860 census didn’t give a number for the Irish military age population, I developed an age-cohort-survival model to estimate it. That predicted a proportional military Irish contribution of about 140,000 with up to 170,000 allowing for post-1858 immigration.

My analysis deals only with the presence of immigrant soldiers in the Union army and navy throughout the war, I have no opinion as a data analyst on “heroes and cowards”. As a combat veteran, I haven’t observed that heroism, or lack thereof, has anything to do with ethnic background or race. The effectiveness of military units is primarily due to leadership, training, adequate supply and sleep. This analysis hasn’t changed that point of view.

Again, I don’t know anything about all this. All I can say is that’s it’s a good example of the challenges of statistical analysis with archival data.


  1. mpledger says:

    I was quite surprised amongst my Irish ancestors how many didn’t marry and how many married at quite a late age. On the wikipedia potato famine page it talks about how this occurred in Ireland because of the harsh economic conditions that resulted after the famine – people couldn’t afford to marry at all or until they were older. If this occurred in North America as well, it could be that the age distribution of the Irish in North America was different (i.e. older) to the Native born/other immigrants and so there were fewer young people to actually be soldiers.

    Also, on the wikipedia page, it said that Irish men and women immigrated in equal numbers so it could also be there were less men in the Irish community compared to other immigrant groups.

  2. Martha (Smith) says:

    I recall hearing as a child that during the U.S. civil war, Irish immigrants to Canada who crossed into the U.S. (whether intentionally or not) were likely to end up being impressed into the Union army.

  3. JCB says:

    Coincidentally for me, having never before seen discussion of Irish immigrants in the American civil war, last night I opened a book on the same subject because it has been longlisted for the current Booker prize. For those interested it is Days Without End by Sebastian Barry.

  4. Steve Sailer says:

    On the other hand, there was the New York Draft Riot of July 1863.

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