Many Irish Catholic Americans hoped the Civil War would prove their loyalty to the nation once and for all. Enlisting in the Union Army in order to show they were just as American as their native-born, Protestant neighbors, they knew they would be judged by how they conducted themselves on the battlefield. Patrick Donahoe, owner and editor of the Boston Pilot, emphatically celebrated Irish Catholic heroism from the First Battle of Bull Run through Appomattox. For Donahoe, their courageous service had killed anti-Catholic nativism once and for all time.
For the twenty-first century historian, measuring bravery is a difficult if impossible thing. Nevertheless, mid-19th century northerners clearly believed that bravery was something that could be proved on the battlefield, and they judged whole groups of men based on their performance. While black bravery at Fort Wagner convinced many whites finally to support the enlistment of African Americans, the rout of the largely German American 11th Corps at Chancellorsville led to a negative nativist backlash against the cowardly “flying Dutchmen.”
In discussing Irish bravery, historians have generally noted that although in the Union Army as a whole one man died of battle wounds for every two that died of disease, in the Irish Brigade this proportion was reversed. The Brigade’s horrific casualties, incurred in many of the most famous battles of the entire war, strongly suggest that Irish Catholics did more than their fair share to save the Union.
Still, the Irish Brigade’s five regiments were not the only ones where Irish soldiers and Catholic chaplains were to be found. Did the ratio of two battlefield deaths to every one from disease hold true across other such regiments? I found that the answer was both yes and no.
In attempting to answer this question, I decided to examine five other regiments known to be Irish Catholic in composition to see if their story reflected that of the Irish Brigade. The units I selected were the 35th Indiana and 10th Ohio Infantry Regiments, both of the Army of the Cumberland; the 6th New York Infantry, which served along the Gulf Coast; and the 9th Massachusetts and 31st New York Infantry Regiments of the Army of the Potomac. All five regiments were staffed by Catholic priests, including both secular and regular clergy.
Overall in these five units, 467 men and officers were killed in action, whereas only 247 died from disease. The resulting ratio of 1.89 men killed in battle for every one who died from disease is very similar to the ratio of casualties in the Irish Brigade. This statistic suggests that many of these Irish Catholic men showed courage under fire and represented their larger community well during the war.
Still, these figures are misleading when the individual regiments are examined. The 6th New York, the 10th Ohio, and the 35th Indiana all saw action during the war, but none of them faced the Army of the Potomac’s grueling campaigns of 1862 and 1863 that resulted in so many casualties in the Irish Brigade. Only the 10th lost about two men in action for every one from disease, with the other two regiments losing more men from disease than battle. All three regiments’ combined battle deaths did not equal the number of men lost by the 9th Massachusetts, which lost nearly five times as many men in battle as from disease. This unit’s staggering battle losses (209), even apart from those sustained by its fellow Army of the Potomac regiment, the 31st New York which lost 68 men, are the only reason the overall casualty ratio for the five regiments in this study approaches the commonly cited figure of two to one for the Irish Brigade.
In sum, these figures cannot measure Irish Catholic soldiers’ bravery definitively vis-a-vis other northern regiments or various racial, ethnic, or religious groups of Americans. Nevertheless, they do suggest to me two useful insights. On the whole, the ratio of battlefield to disease fatalities was above average in Irish Catholic units, perhaps explaining why many Irish Catholics back home were both proud of their men’s service while increasingly dismayed at the war’s high cost to their community. And, on a more specific, regimental scale, the Irish Brigade experience of the war cannot be uncritically taken as representative of Irish Catholic military service in the Union Army. More attention to non-Irish Brigade units, their men, officers, and chaplains will be necessary to form a more balanced understanding of the Irish and Catholic northern military experience.
 William B. Kurtz, Excommunicated from the Union: How the Civil War Created a Separate Catholic America (New York: Fordham University Press, 2016), 1, 37–38, 127–128.
 John David Smith, Lincoln and the U.S. Colored Troops (Carbondale: Southern Illinois University Press, 2013), 76; Christian B. Keller, Chancellorsville and the Germans: Nativism, Ethnicity, and Civil War Memory (New York: Fordham University Press, 2007), 2–4.
 David Power Conyngham, The Irish Brigade and its Campaigns, “Introduction,” Lawrence Frederick Kohl, ed. (New York: William McSorley & Co., 1867; reprint, New York: Fordham University Press, 1994), x.
 In addition to using William F. Fox’s famous study, Regimental Losses In the American Civil War, 1861-1865 (1889) to determine the number of men killed or mortally wounded in battle, the number of men who died from disease in these regiments was retrieved from http://www.civilwardata.com/. My data table does not record all deaths in the regiments, as scores of men in the units also died from various accidents and other causes during the war.