Schley's group was among the many Pennsylvania Dutch (ethnic Germans) (as well as Scots-Irish and French and later Irish) who migrated south and westward in the late-18th century. Frederick was an important stop along the migration route that became known as the Great Wagon Road, which came down from Gettysburg, Pennsylvania and Emmitsburg, Maryland and continued south following the Great Appalachian Valley through Winchester and Roanoke, Virginia. Another important route continued along the Potomac River from near Frederick, to Hagerstown, where it split. One branch crossed the Potomac River near Martinsburg, West Virginia and continued down into the Shenandoah valley. The other continued west to Cumberland, Maryland and ultimately crossed the Appalachian Mountains into the watershed of the Ohio River. Thus, British General Edward Braddock marched his troops (including the youthful George Washington) west in 1755 through Frederick on the way to their fateful ambush near Fort Duquesne (later Fort Pitt, then Pittsburgh) during the French and Indian War. However, the British after the Proclamation of 1763 restricted that westward migration route until after the American Revolutionary War. Other westward migrants continued south from Frederick to Roanoke along the Great Wagon Road, crossing the Appalachians into Kentucky and Tennessee at the Cumberland Gap near the Virginia/North Carolina border.