Some 150,000 Irish-American immigrants served in the Union Army during the Civil War (1861-1865), most of them from Boston, New York and Chicago, and about 40,000 fought in the Confederate Army. The best known unit was the Irish Brigade of the Union Army of the Potomac, which distinguished itself at Antietam and, particularly, at Fredericksburg, where its sacrificial bravery astonished friend and foe alike. Famous regiments were New York's 'Fighting 69th', the 9th Massachusetts, 116th Pennsylvania, 23rd Illinois and 35th Indiana. Two Louisiana Confederate brigages from New Orleans were almost...