Where Were ‘Irish’ Soldiers From?: A Case Study of the 23rd Illinois Infantry

The ‘green flag’ regiments of the Union army remain the most recognisable expression of Irish involvement in the American Civil War. These ethnic Irish units were proud of their heritage and sought to combine this with their loyalty to Union, often by carrying green flags amongst their colours or bearing epithets such as the ‘Irish Brigade.’ But where were these ‘Irish’ soldiers from? How many of the men were Irish emigrants, how many were Irish-American, and how many had no connection to Ireland? Using the nativity records of one Irish regiment, the 23rd Illinois Infantry (‘Mulligan’s Irish Brigade’) this is the first in a series of posts that seeks to explore this question.

In order to gather data for this discussion, information on the company, place and country of birth was recorded for 1,585 men of the 23rd Illinois, using the Illinois Civil War Muster and Descriptive Rolls Database as a source of data.* Examining the nativity of Civil War soldiers in isolation is of course an overly simplistic method of determining origin. It does not allow for where a soldier considered himself to be from, a factor often more important that the location of his birth. For example a New York or Canadian born Irishman would in many cases have had just as strong a sense of his ‘Irishness’ as someone born in Ireland. This was particularly true of the pre-war years when anti-Irish sentiment had a binding effect on members of the Irish-American community. In addition, it should be noted that assessing all the men as one group does not account for variables such as when they joined the unit (many Irish regiments lost some of their Irish character later in the war, when non-Irish conscripts were drafted in) or their motivation for joining. With these caveats in mind, it is nonetheless worthwhile to review this data, as it provides an insight into the levels of Irish-born emigrants in the ranks, may indicate where Irish-American communities were located, and suggests the proportion of ‘non-Irish’ in the ranks.

Map of Europe showing nativity of members of the 23rd Illinois Infantry (Sara Nylund)

Map of Europe showing nativity of members of the 23rd Illinois Infantry (Sara Nylund)

The 23rd Illinois Infantry were formed in Chicago under the leadership of Irish-American Colonel James A. Mulligan. They were engaged at Lexington, Missouri in September 1861 where the majority of the regiment was captured. An order mustering out the unit following its exchange was countermanded and the regiment was subsequently reformed. They served as prison guards into the middle of 1862 when the 23rd moved  to Harper’s Ferry, Virginia. They would remain in West Virginia and Virginia for the remainder of the war. The regiment saw service in the 1864 Valley Campaign (in which Colonel Mulligan was killed) and that August was consolidated into five companies, becoming the 23rd Illinois Veteran Volunteers. In late 1864 it was transferred to the Army of the James with whom it served at Petersburg and Appomattox. During the course of the conflict the regiment lost 4 officers and 50 men killed or mortally wounded, and 2 officers and 93 men from disease. (1)

Once the nativity data was collected, percentages were calculated for the total number of soldiers born in each country based on the 1,585 records viewed. The results are set out in the table below:

Country of Birth Number of Soldiers % of Total
Ireland 682 43.0
United States 407 25.7
None Recorded 315 19.9
England 47 3.0
Germany 42 2.6
Canada 39 2.5
Scotland 21 1.3
France 15 0.9
Norway 5 0.3
Sweden 3 0.2
Switzerland 3 0.2
Born at Sea 2 0.1
Holland 2 0.1
Wales 2 0.1

What is immediately apparent is the Irish character of the 23rd Illinois. If we exclude the men for which no record of nativity survives, those of Irish birth account for 53.8% of the remaining total. This suggests that over half of the men who served in the regiment were of Irish birth. In addition, surname evidence indicates that the majority of those born outside Ireland were from Irish-American communities. This said, caution does need to be exercised when using surnames as an indicator of ethnicity, as many Irish-born men often bear atypical Irish names, and vice-versa. However there are clear examples in the 23rd linking men born in North-America to the Irish-American community; for example a number of cases where an older brother born in Ireland served with a younger brother born in the United States.

It is also possible that nativity evidence for those born within North America can provide indicators as to the locations of Irish-American populations or ports of entry. Of the 407 soldiers who were born within the United States, it is perhaps somewhat surprising that only 150 of them hailed from Illinois and Michigan, the two states where companies of the 23rd Illinois were raised. This accounts for less than 10% of the total number of men in the regiment. Indeed the highest nativity figures from the United States are from New York, where 122 of the men were born. Locations such as Canada and the states of New York, Massachusetts, Pennsylvania and to a lesser extent Ohio were often where Irish emigrants found themselves shortly after arrival in the country, and cities in each location soon had thriving Irish-American communities. It seems likely that at least some of the men in the 23rd were born into such communities in these states, and later moved on to Illinois and Michigan, either to improve their lot or specifically join Mulligan’s regiment.

Map of North America showing nativity of members of the 23rd Illinois Infantry (Sara Nylund)

Map of North America showing nativity of members of the 23rd Illinois Infantry (Sara Nylund)

There are of course those who had no connection whatsoever to the Irish-American community in the ranks of the 23rd. Although some of the names on the rolls of the unit are clearly ‘native’ in character, perhaps the most obvious evidence for this are men from countries such as France and Germany, who had no specific reason to seek out an Irish regiment to join. It is most likely that they enrolled in companies which were organising where they lived, and did not make their decision based on ethnic associations. It is clear that this non-Irish element of Americans and Europeans formed a sizeable proportion of the 23rd and must have made a significant contribution to the unit’s character.

The nativity information from the 23rd Illinois clearly illustrates the regiment’s Irish character, with those born in Ireland forming the largest group in the ranks. The unit also attracted significant numbers of North-American born members of the Irish-American community, as well as a number of men who had no particular ties to Ireland. Although each regiment in the Union army, Irish or otherwise, undoubtedly had its own character and set of circumstances which influenced its make-up, it is nonetheless of interest to analyse the origins of the men who formed one of these units. It is intended in the future to compliment this survey by looking at the nativity of a non-Irish regiment to note the degrees of difference, as it was in such formations that the majority of Irish in the American Civil War served. The next post in this series will look at where in Ireland the Irish-born men of the 23rd Illinois came from, to examine if any patterns or concentrations are discernible.

(1)  Illinois AG ReportCivil War Soldiers and Sailors System;

*Efforts were made to avoid duplication of individuals due to contemporary spelling discrepancies and multiple records, though some margin of error is unavoidable. Field officers were not included.

**Special thanks to Sara Nylund for preparing the illustrations for this post.


Civil War Soldiers and Sailors System

Illinois Adjutant General’s Report: Regimental and Unit Histories, Containing Reports for the Years 1861- 1866

Illinois Civil War Muster and Descriptive Rolls Database


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Categories: 23rd Illinois, Discussion and Debate

Author:Damian Shiels

I am an archaeologist based in Ireland, specialising in conflict archaeology.

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7 Comments on “Where Were ‘Irish’ Soldiers From?: A Case Study of the 23rd Illinois Infantry”

  1. December 5, 2011 at 7:04 pm #

    Looking at these regiments from the other side of the pond, you might wonder why there are many Americans in Irish-American regiments. However you must realize the only way irish regiments could muscle into the power structure here in the States was thru their one and only conduit–the Democratic party. Andy Jackson did much to broaden the rules for voting franchise for the regular guy. Although Andy was of Ulster stock, he personally hated the English and was called the “Irish President” meaning Irish Catholic or Irish Nationalist. If one looks at the early Irish militia companies in the 1840’s, one finds that they are captained by a prominent American Democrat politician. In Philadelphia Robert Tyler, Jr ran the Democratic organization and had his younger brother John Tyler Jr (also the son of the former prez) was captain of the Meagher Guards. One must remember that when the Civil War broke out Colonel Mulligan (born in NY) 23rd Illinois, Colonel Lytle 10th Ohio, another powerful American Democrat from Cincinnati, and JT Owen, 24th &69th Pa, a former Democrat legislature member and Democrat in the Philly city council were chosen not for military credentials —but for political reasons—to meet the WASP’s head on with an ethnic tool in the power game.

  2. December 6, 2011 at 12:48 am #

    Another interesting anecdote about Democrat politics raising Union regiments is the Excelsior Brigade from New York. This brigade was formed by former NY Congressman Daniel Sickles. I was approached by a friend who bought the discharge of a soldier who enlisted in the Excelsior Brigade, but was a resident of Greensburg, Pennsylvania and had been born in Germany.

    My friend said to me—“Who is this guy and why isn’t he in a Pennsylvania regiment?”

    He’s a Democrat, I replied.


    Well this is very easy to explain. Sickles contacted his Democrat friends in other towns and raised companies with local Democrat officers beating the brush among the Democrat faithful for recruits. I know that Greensburg, Philadelphia, and Pittsburgh all raised companies for Sickles” Brigade. Since most northern Democrats were Irish and Germans, most Excelsior Brigade companies are heavy with immigrants.One of the most noted Irishmen is Captain Frank Moran, who later wrote the often reprinted escape of Colonel Rose and Major Hamilton from Libby Prison in Richmond, Virginia. Moran was captured with the Excelsior Brigade in the Wheatield at Gettysburg on 2 July 1863. His article first appeared in Century magazine in the 18880’s.

  3. December 6, 2011 at 3:15 pm #

    Hi MIchael,

    Thanks for posting! That is a good point- I particularly recall coming across that in relation to Lytle’s selection for the 10th Ohio. There is mention as well of Irish soldiers attempting to get transferred to the 23rd as they saw it as a place where they could escape perceived religious prejudice in other regiments, so I wonder was it see as a ‘haven’ by some where they could seek advancement. Your insights into the connection with the Democratic party are interesting. Although obviously the strong links between the Irish community and the Democratic party must have played a part, I hadn’t been aware about the potential to cross state lines to be part of a Democratic regiment. It makes perfect sense though, and it would seem likely that it certainly had an affect on the 23rd. Thanks for highlighting that- the influencing factors on how these units were composed is a really fascinating topic!

    Kind Regards,


  4. January 22, 2012 at 4:10 am #

    Really interesting article. While some of the Canadians and English may have been the children of Irish immigrants transiting to the US, the other country’s of nativity point to just how multi-culti American was becoming.

    • January 23, 2012 at 7:26 pm #

      Hi Pat,

      Many thanks- I agree absolutely- it must have been interesting for men like the Swedes and Germans on a couple of levels, not only in a US regiment but an Irish US regiment at that!

      Kind Regards,



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    […] last post looked at the nativity of soldiers in the 23rd Illinois Infantry, based on analysis of records […]

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