In 1775, Hugh Rogan and Daniel Carlan left Derry for Philadelphia, Pennsylvania. This was the most common port for immigrants from Ireland, both Irish Catholics and Ulster Scots who were generally protestant, to enter the American colonies. More than 250,000 people left Northern Ireland before 1776 and another 100,000 followed after passenger service resumed following the Revolutionary War in 1783. From Philadelphia, thousands of men, women, and children moved by horseback, on foot, and by wagon, south into Virginia and the Carolinas and through the Cumberland Gap into what would be Tennessee and the Upland South.
Rogan and Carlen followed this route. Some sources indicate that Hugh, on learning that the colonies were in rebellion against the Crown was anxious to join in the fighting against the British and he was included in the Henry County, Virginia Militia List for 1779 under the command of Capt. Daniel Carlen. Carlen took up residence in the area of Virginia near the North Carolina border.
In 1779, Hugh joined the team, lead by Dr. Thomas Walker and Gen. Daniel Smith who were surveying the boundaries of western Virginia and North Carolina. It was during this expedition that Hugh Rogan first came into the Cumberland River Valley, perhaps spending several months in the area. The remainder of his life would be closely associated with this wilderness territory that he would help to settle.