There were about 150,000 Irishmen — many of whom were not American citizens at the time — who served in the Union Army during the Civil War. Many were patriotic towards their new home, while some hoped that honorable service might help reduce some of the blatant discrimination against the Irish in the country.
As the war deepened, their enthusiasm waned, but from the start of the war until 1863, the all-Irish units often distinguished themselves as courageous and ferocious fighters. Many Irish joined regular units, but the 63rd, 69th, and 88th New York Regiments were all-Irish and became known as the Irish Brigade. Later the 28th and 29th Massachusetts and the 116th Pennsylvania were added.
Putting the units together was part of a PR campaign by the Union to gain support. Many Irish were sympathetic to the Confederates, who they saw as a group trying to overcome a suppressive government, much like they’d experienced in Ireland with the British. They also were concerned about newly freed slaves crowding the labor market. The regiments were offered bonuses, extra rations, and Catholic chaplains as incentives.
The Brigade took heavy casualties at the Battle of Sharpsburg (Antietam) and the Battle of Fredericksburg. At the Battle of Gettysburg, about 320 of the remaining 530 men were killed. There is a monument to them on the battlefield.
By 1863, many Irish felt their units were being used as cannon fodder and when the draft lottery rules required all men from 21 to 45 as eligible unless they paid a substitute or handed over a $300 fee, many were outraged. This lead to draft riots in New York City where at least 120 people died.
The Brigade was officially disbanded in 1864. Its commander, Thomas Francis Meagher, later became Acting Governor of Montana after the war.
Sources:
“The Irish Brigade.” history.com
Another good one. Thanks!