There is an interesting take on the Irish in the Civil War and the American attitude toward them in general in a book called "Myles Keogh: the Life and Legend of an Irish Dragoon in the Seventh Cavalry," eds. John P. Langellier, Kurt Hamilton Cox, and Brian Pohanka. It's kind of hard to find, but may be available as an inter-library loan. It says, among other things, that Phil Sheridan found it more politic to play down his Irish ancestry because of prejudice. There is also a website that discusses the issue:http://www.thewildgeese.com/pages/plains.html