There is a very interesting program currently running on the history channel about the Irish in America. The first wave were the Ulster Irish, or the Scots-Irish that had been banished or fled from South Scotland to Northern Ireland due to religious persecution. No doubt hunger was a constant issue as well. But around the 1650's, they began to look for freedon and opportunity in the colonies, and ultimately became the backbone of the revolution and the founding members of the US, including Andrew Jackson. The second wave was the 1800-1850's seeking refuge from the potato crop failures and as well as English rule. Much of what was produced in Ireland in the way of food and product was shipped back to England while the Catholic Irish in the south suffered famine and disease.
Many of the Irish were immediately inscripted into the infantry - on both sides - and fought in the civil war.

The name Crayton itself seems to still be in dispute. There are Craytons as well as Creightons in Scotland and Ireland.