Kat: the folks living on either side of the (very narrow) water separating the northeastern corner of Ireland from the west coast of Scotland have always been fairly closely related. The religious/national divisions of 16th century introduced a degree of animosity between Catholic Irish and Presbyterian Scots that probably didn't exist before. And for a while the "nonconformist" Presbyterians were only slightly less persecuted by the Anglican establishment than were the Papists.

In any event, Cromwell forced the Catholic natives of Ulster off their highly desireable farmlands, banished them to the relatively barren rocky west, and forcibly repopulated the area ("plantation") with Scottish peasants/farmers from just across the water, thereby "planting" a more cooperative population, forefathers of the future Orangemen and Loyalists.

Not long afterwards, within a generation or two, the offspring/descendants of these same people made another move across the ocean to serve a similar purpose in populating the British Colonies of America (most going to the southern colonies, many as indentured servants). These were and are the "Scotch-Irish" who comprise a huge part of the US population and have produced a large number of Presidents, from Andrew Jackson through Reagan.