Catoctin Mountain, which comes down out of Maryland at Point of Rocks. The low-lying ridge extends through the county just west of Leesburg to Aldie, where it meets with Bull Run Mountain at the Loudoun-Prince William County border. To the west of the ridge lies the fertile Loudoun Valley. The northern portion of the Loudoun Valley is bisected by Short Hill Mountain, which extends from the Potomac to just south of Hillsboro. The Charlestown Pike (present-day Route 9) ran through the Hillsboro Gap in Short Hill at Hillsboro into Jefferson County, while the Winchester Turnpike ran to the south of the mountain. Despite its name, Short Hill Mountain is an imposing feature, even today, and kept the area to its west, known as Between the Hills, isolated from the rest of the county. Settlement, slavery and sentiments The settlement of Loudoun County occurred through two distinct patterns. First, between 1725 and 1730, English settlers from the Tidewater region moved into the areas east of Catoctin Mountain and in the southern Loudoun Valley. They brought with them many of the Cavalier attitudes associated with Virginians, as well as plantation-style agriculture and its use of slaves. Among these settlers were many of Virginia's aristocratic families including the Masons, Lees and Carters, the latter of whom established Oatlands Plantation, the largest in the county. Citizens living in this part of the county generally supported the Confederacy once war erupted, regardless of slave ownership. Then, between 1730 and 1735, Quaker and German settlers moved south from Pennsylvania into the northern Loudoun Valley, establishing small farming operations in the Catoctin Valley around the areas of Lovettsville, Waterford, and as far south as Lincoln. The small, self-sufficient nature of the farms they established, as well as their religious convictions, precluded the use of slaves in these areas. During the Civil War, this region stayed loyal to the Union cause. In addition, throughout the 18th century, Scotch-Irish settlers trickled into the county settling the more mountainous regions along the Catoctin and Blue Ridge Mountain and the Between the Hills valley. These settlers were generally poor and had small land holdings with few if any slaves; still, they tended to support the Confederate cause. The 1860 census showed 670 slave owners holding 5,501 slaves in the county of 21,774 inhabitants (there were also 1,252 free blacks). Only 50% of slaveholders in the county owned more than five slaves,