[Wallace T.]

The largest portion of the Irish who fought in the Continental Army was Scotch-Irish, who were descendants of Lowland Scots, with some Highland Scots, Northern English, and "original Irish" mixture, who emigrated to Northern Ireland in the 16th and 17th Centuries, as part of an attempt by the Tudor and Stuart monarchs to establish loyal subjects in Ireland. The Lowland Scots spoke Scots English, a dialect of English, and not a Celtic language. The Celtic languages had died out in the Lowlands during the Middle Ages. The Lowlanders were linguistically Anglo-Saxon and at least partially Germanic (Anglo Saxon and Scandinavian) by race and culture.

[Verginius Rufus]

There could be some Irish admixture in the Lowlands (from the early middle ages, when Gaelic was brought from Ireland). Apparently some of the old place names in the far southern part of mainland Scotland are P-Celtic (going back to people related to the Welsh and the Cornish, rather than to Q-Celtic immigrants from Ireland).