There's been a lot of talk about the Scots-Irish in America, thanks mostly to James Webb's new book, Born Fighting. InstaPundit suggests that much of the same ground was covered in Albion's Seed, a few years ago.
Let me add my own plug. Perhaps the earliest treatment of the Scots-Irish, and still one of the best, was Theodore Roosevelt's history of the "backwoodsmen," which makes up much of The Winning of the West, Volume 1. Roosevelt describes these people, who he says were the first and last to bypass civilization and seek out the wild places of the frontier:
Thus the backwoodsmen lived on the clearings they had hewed out of the everlasting forest; a grim, stern people, strong and simple, powerful for good and evil, swayed by gusts of stormy passion, the love of freedom rooted in their very hearts' core. Their lives were harsh and narrow; they gained their bread by their blood and sweat, in the unending struggle with the wild ruggedness of nature. They suffered terrible injuries at the hands of the red men, and on their foes they waged a terrible warfare in return. They were relentless, revengeful, suspicious, knowing neither ruth nor pity; they were also upright, resolute, and fearless, loyal to their friends, and devoted to their country.If any other account has captured the Scots-Irish so well as that, I haven't seen it.