Irish Americans in the American Civil War Pre - 1861 Irish immigration . Although Irish immigration to the United States has taken place since colonial times ( Six Declaration of Independence signers were of Irish descent and Andrew Jackson was partially Irish ) , worsening conditions ( under British rule ) in Ireland - especially the Great Famine - caused many Irish to emigrate in the mid - 19th century . An Irish immigrant , having suffered through an arduous overseas journey , would have been thrust into a terrible situation , as many were poor and unused to American customs . Soon , however , the number of Irish - Americans in some cities grew so great that immigrant Patrick Murphy stated " New York is a grand handsome city . But you would hardly know you had left Ireland . " American customs , once utterly foreign to the immigrants , became blended with traditional ones , forming a distinct Irish - American culture . The American Civil War . Most Irish - Americans had settled in the northern , anti - slavery American states and were thus called up to service when southern , slaveholding states seceded and formed the Confederacy in 1861 . Many Irish - Americans formed their own units , which embraced Irish customs such as Catholic masses and priests . The first two casualties of the Civil War were Irish , as well . The 1863 Draft Riots . On March 3 , 1863 , Congress passed the Enrollment Act which required single men age 20 to 45 and married men up to age 35 to register for the draft . This act angered many whites , mainly Irish , who then living in northern states as immigrants signed as U . S . citizens were now expected to fight for the new nation , not realizing it too made the immigrants liable for the draft . It also add fuel to the fire when blacks , mostly freed slaves , were excluded from the draft and the Irish feared that freed slaves would migrate to the North and add further competition to the labor market . Many Irish saw this as a " rich man ' s war and a poor man ' s fight " since the policies of substitution and commutation were controversial practices that allowed drafted citizens to opt out of service by either furnishing a suitable substitute to take the place of the drafted , or paying $ 300 . Both of these provisions were created with the intention of softening the effect of the draft on pacifists , the anti - draft movement , and the propertied classes . The result however was general public resentment of both policies . A few days after the Enrollment Act was passed , in March 6 , 1863 , the Detroit Race Riot of 1863 erupted in Detroit , Michigan , as Irish rioted for days over the draft as well as targeting against the blacks . Although not as destructive , the fear was about to come 4 months later . In July 13 – 16 , as the first draft were to be held in New York City , the Irish then launched the 1863 New York City draft riots . Stores were looted and newspaper buildings that supported the Union were ransacked and burned to the ground . The rioters then targeted blacks as many saw the American Civil War as a war to free the slaves and blamed them for the draft as well as the war . Many blacks were caught by the mob , stabbed , and lynched as a result . When the draft riots started , the New York State Militia was absent because they were sent to assist Union troops in Pennsylvania , thus leaving the New York City Police Department the only force to put down the riot . The police were unable to handle a crowd that has 10x more population than that and the rioting continued on and on . Two days later , word came to announced that the draft had been suspended . Federal troops returning from the Battle of Gettysburg were sent to the city to quell down the riot and peace was finally restored in the streets of New York City over a day later . Over 121 people died in the draft riots in New York City . The 1863 New York City Draft riots were the largest civil insurrection in American history . Irish service to the Union . The northern states remained loyal to the United States government , which was led by President Abraham Lincoln . Irish - Americans living in the Union states often formed their own regiments , notably the 69th New York State Volunteers . The Volunteers flew a green flag with a golden harp on it , symbolizing Ireland . Seven Union generals were Irish - born < citation needed > and 150 , 000 Irish - Americans fought for the Union during the war . At the 1862 Battle of Fredericksburg , the Union Irish Brigade charged up Marye ' s Heights , suffering 41 . 4 % casualties . During the Battle of Gettysburg in 1863 , the Irish Brigade held a Catholic mass before battling Confederate troops . Irish - Americans in Confederate service . Although significantly fewer Irish lived in the Confederate States of America , six Confederate generals were Irish - born . Units such as the Charleston Irish Volunteers attracted Confederate Irish - Americans in South Carolina , the 24th Georgia Volunteer Infantry followed General Thomas Reade Rootes Cobb , while Irish Tennesseans could join the 10th Tennessee Infantry Regiment . The 5th Missouri Infantry , commanded by Colonel Joseph Kelly , was called " the Sons of Erin . " , or Kelly ' s Irish Brigade . Although this unit was only a regiment , it is sometimes dubbed " The Confederate Irish Brigade . " The Louisiana Tigers , first raised by Major Chatham Roberdeau Wheat , had a large number of Irish American members .